WIP: Integrate Spotbugs

See:
- https://github.com/spring-projects/spring-boot/releases/tag/v2.7.3
- https://github.com/spring-projects/spring-boot/compare/v2.7.2...v2.7.3

.github/workflows/build.yaml

@@ -0,0 +1,37 @@
+name: Build and verify
+on:
+  pull_request:
+  push:
+    branches:
+      - 'master'
+jobs:
+  build:
+    runs-on: ubuntu-22.04
+    strategy:
+      matrix:
+        jdk: [ 11.0.16, 17.0.4 ]
+    steps:
+        # We run the build twice for each supported JDK: once against the
+        # original Error Prone release, using only Error Prone checks available
+        # on Maven Central, and once against the Picnic Error Prone fork,
+        # additionally enabling all checks defined in this project and any
+        # Error Prone checks available only from other artifact repositories.
+      - name: Check out code
+        uses: actions/checkout@v3.0.2
+      - name: Set up JDK
+        uses: actions/setup-java@v3.4.1
+        with:
+          java-version: ${{ matrix.jdk }}
+          distribution: temurin
+          cache: maven
+      - name: Display build environment details
+        run: mvn --version
+      - name: Build project against vanilla Error Prone
+        run: mvn -T1C install
+      - name: Build project with self-check against Error Prone fork
+        run: mvn -T1C clean verify -Perror-prone-fork -Pnon-maven-central -Pself-check -s settings.xml
+      - name: Remove installed project artifacts
+        run: mvn build-helper:remove-project-artifact
+
+# XXX: Enable Codecov once we "go public".
+# XXX: Enable SonarCloud once we "go public".

.gitignore

@@ -0,0 +1,11 @@
+# General Java development.
+.attach_pid*
+.classpath
+.DS_Store
+.factorypath
+.idea
+.project
+.settings
+target
+*.iml
+*.swp

.mvn/jvm.config

@@ -0,0 +1,13 @@
+-XX:ReservedCodeCacheSize=512m
+-XX:SoftRefLRUPolicyMSPerMB=10
+-XX:+UseParallelGC
+--add-exports=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED
+--add-exports=jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED
+--add-exports=jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED
+--add-exports=jdk.compiler/com.sun.tools.javac.model=ALL-UNNAMED
+--add-exports=jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED
+--add-exports=jdk.compiler/com.sun.tools.javac.processing=ALL-UNNAMED
+--add-exports=jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED
+--add-exports=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED
+--add-opens=jdk.compiler/com.sun.tools.javac.code=ALL-UNNAMED
+--add-opens=jdk.compiler/com.sun.tools.javac.comp=ALL-UNNAMED

.mvn/maven.config

@@ -0,0 +1 @@
+--batch-mode --errors --strict-checksums

.renovaterc.json

@@ -0,0 +1,22 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "packageRules": [
+    {
+      "matchPackagePatterns": [
+        "^org\\.springframework:spring-framework-bom$",
+        "^org\\.springframework\\.boot:spring-boot[a-z-]*$"
+      ],
+      "separateMinorPatch": true
+    },
+    {
+      "matchPackagePatterns": [
+        "^com\\.palantir\\.baseline:baseline-error-prone$"
+      ],
+      "schedule": "* * 1 * *"
+    }
+  ],
+  "reviewers": [
+    "rickie",
+    "Stephan202"
+  ]
+}

.travis.yml

@@ -1,35 +0,0 @@
----
-dist: bionic
-language: java
-jdk: openjdk11
-addons:
-  sonarcloud:
-    organization: picnic-technologies
-    token: "${SONARCLOUD_TOKEN}"
-install:
-  - mvn io.takari:maven:wrapper
-script:
-  # We run the build twice: once against the original Error Prone release, and
-  # once against the Picnic Error Prone fork.
-  - ./mvnw clean install
-  - ./mvnw clean install -Perror-prone-fork -s settings.xml
-  # XXX: Enable SonarCloud once we "go public".
-  # ./mvnw jacoco:prepare-agent surefire:test jacoco:report sonar:sonar
-  - ./mvnw jacoco:prepare-agent surefire:test jacoco:report
-before_cache:
-  # Don't cache the artifacts we just generated, for multiple reasons: (1) we
-  # shouldn't need them next time around and (2) if we do, that indicates a
-  # dependency issue which might otherwise go unnoticed until next time we bump
-  # the project's version (i.e., when tagging).
-  - find "${HOME}/.m2/repository" -depth -name '*-SNAPSHOT' -exec rm -r '{}' \;
-cache:
-  directories:
-    # The local Maven repository in which third party dependencies are stored.
-    - ${HOME}/.m2/repository
-    # The Takari Maven Wrapper's storage for downloaded Maven distributions.
-    - ${HOME}/.m2/wrapper
-    # The SonarQube analysis cache.
-    - ${HOME}/.sonar/cache
-# XXX: Enable Codecov once we "go public".
-#after_success:
-#  - bash <(curl -s https://codecov.io/bash)

apply-error-prone-suggestions.sh

@@ -0,0 +1,25 @@
+#!/usr/bin/env bash
+
+# Compiles the code using Error Prone and applies its suggestions. The set of
+# checks applied can optionally be restricted by name.
+#
+# As this script may modify the project's code, it is important to execute it
+# in a clean Git working directory.
+
+set -e -u -o pipefail
+
+if [ "${#}" -gt 1 ]; then
+  echo "Usage: ./$(basename "${0}") [PatchChecks]"
+  exit 1
+fi
+
+patchChecks=${1:-}
+
+mvn clean test-compile fmt:format \
+  -T 1.0C \
+  -Perror-prone \
+  -Perror-prone-fork \
+  -Ppatch \
+  -Pself-check \
+  -Derror-prone.patch-checks="${patchChecks}" \
+  -Dverification.skip

error-prone-contrib/README.md

@@ -15,13 +15,23 @@ This is a [Maven][maven] project, so running `mvn clean install` performs a
 full clean build. Some relevant flags:
 - `-Dverification.warn` makes the warnings and errors emitted by various
   plugins and the Java compiler non-fatal, where possible.
-- `-Dverification.skip` disables various non-essential plugins and compiles the code with
-  minimal checks (i.e. without linting, Error Prone checks, etc.)
-- `-Perror-prone-fork` builds the code and runs the tests against Picnic's
-  [Error Prone fork][error-prone-fork-repo] (hosted on
-  [Jitpack][error-prone-fork-jitpack]). Refaster templates are only tested when
-  the fork is used, because they rely on changes in the unmerged PR
-  [google/error-prone#1239][[error-prone-issue-1239].
+- `-Dverification.skip` disables various non-essential plugins and compiles the
+  code with minimal checks (i.e. without linting, Error Prone checks, etc.)
+- `-Dversion.error-prone=some-version` runs the build using the specified
+  version of Error Prone. This is useful e.g. when testing a locally built
+  Error Prone SNAPSHOT.
+- `-Perror-prone-fork` run the build using Picnic's [Error Prone
+  fork][error-prone-fork-repo], hosted on [Jitpack][error-prone-fork-jitpack].
+  This fork generally contains a few changes on top of the latest Error Prone
+  release.
+
+Two other goals that one may find relevant:
+- `mvn fmt:format` formats the code using
+  [`google-java-format`][google-java-format].
+- `mvn pitest:mutationCoverage` runs mutation tests using [PIT][pitest]. The
+  results can be reviewed by opening the respective
+  `target/pit-reports/index.html` files. For more information check the [PIT
+  Maven plugin][pitest-maven].
 
 When loading the project in IntelliJ IDEA (and perhaps other IDEs) errors about
 the inaccessibility of `com.sun.tools.javac.*` classes may be reported. If this
@@ -41,7 +51,7 @@ Some pointers:
   checks][error-prone-criteria]. Most guidelines described there apply to this
   project as well, except that this project _does_ focus quite heavy on style
   enforcement. But that just makes the previous point doubly important.
-- Make sure that a checks's (mutation) coverage is or remains about as high as
+- Make sure that a check's (mutation) coverage is or remains about as high as
   it can be. Not only does this lead to better tests, it also points out
   opportunities to simplify the code.
 - Please restrict the scope of a pull request to a single feature or fix. Don't
@@ -225,22 +235,108 @@ The following is a list of checks we'd like to see implemented:
   `expr.switchIfEmpty(Single.error(...))`, so that an application-specific
   exception is thrown instead of `NoSuchElementException`.
 - An RxJava-specific check which flags use of `#assertValueSet` without
-  `#assertValueCount`, as the former method doesn't do what one may intuitivily
+  `#assertValueCount`, as the former method doesn't do what one may intuitively
   expect it to do. See ReactiveX/RxJava#6151.
 
+### Refaster extension ideas
+
+XXX: This section should live elsewhere.
+
+It's much easier to implement a Refaster rule than an Error Prone bug checker,
+but on the flip side Refaster is much less expressive. While this gap can never
+be fully closed, there are some ways in which Refaster's scope of utility could
+be extended. The following is a non-exhaustive list of ideas on how to extend
+Refaster's expressiveness:
+- Allow more control over _which_ methods are statically imported by
+  `@UseImportPolicy`. Sometimes the `@AfterTemplate` contains more than one
+  static method invocation, and only a subset should be statically imported.
+- Provide a way to express that a lambda expression should also match an
+  equivalent method reference and/or vice versa.
+- Provide a way to express that certain method invocations should also be
+  replaced when expressed as a method reference, or vice versa. (The latter may
+  be simpler: perhaps the rule `T::m1` -> `T::m2` can optionally be interpreted
+  to also cover `T.m1(..)` -> `T.m2(...)`.)
+- Some Refaster refactorings (e.g. when dealing with lazy evaluation) are valid
+  only when some free parameter is a constant, variable reference or some other
+  pure expression. Introduce a way to express such a constraint. For example,
+  rewriting `optional1.map(Optional::of).orElse(optional2)` to `optional1.or(()
+  -> optional2)` is not behavior preserving if evaluation of `optional2` has
+  side-effects.
+- Similarly, certain refactoring operations are only valid if one of the
+  matches expressions is not `@Nullable`. It'd be nice to be able to express
+  this.
+- Generalize `@Placeholder` support such that rules can reference e.g. "any
+  concrete unary method". This would allow refactorings such as
+  `Mono.just(constant).flatmap(this::someFun)` -> `Mono.defer(() ->
+  someFun(constant))`.
+- Sometimes a Refaster refactoring can cause the resulting code not to compile
+  due to a lack of generic type information. Identify and resolve such
+  occurrences. For example, an `@AfterTemplate` may require the insertion of a
+  statically imported method, which can cause required generic type information
+  to be lost. In such a case don't statically import the method, so that the
+  generic type information can be retained. (There may be cases where generic
+  type information should even be _added_. Find an example.)
+- Provide a way to express "match if (not) annotated (with _X_)". See #1 for a
+  motivating example.
+- Provide a way to place match constraints on compile time constants. For
+  example, "match if this integer is less than 2" or "match if this string
+  matches the regular expression `X`".
+- Provide a way to express transformations of compile-time constants. This
+  would allow one to e.g. rewrite single-character strings to chars or vice
+  versa, thereby accommodating a target API. Another example would be to
+  replace SLF4J's `{}` place holders with `%s` or vice versa. Yet another
+  example would be to rewrite `BigDecimal.valueOf("<some-long-value>")` to
+  `BigDecimal.valueOf(theParsedLongValue)`.
+- More generally, investigate ways to plug in in fully dynamic behavior, e.g.
+  by providing hooks using which arbitrary predicates/transformations can be
+  plugged in. The result would be a Refaster/`BugChecker` hybrid. A feature
+  such as this could form the basis for many other features listed here. (As a
+  concrete example, consider the ability to reference
+  `com.google.errorprone.matchers.Matcher` implementations.)
+- Provide a way to match lambda expressions and method references which match a
+  specified functional interface. This would allow rewrites such as
+  `Mono.fromCallable(this::doesNotThrowCheckException)` ->
+  `Mono.fromSupplier(this::doesNotThrowCheckException)`.
+- Provide an extension API using which methods or expressions can be defined
+  based on functional properties. A motivating example is the Java Collections
+  framework, which allows many ways to define (im)mutable (un)ordered
+  collections with(out) duplicates. One could then express things like "match
+  any method call with collects its inputs into an immutable ordered list". An
+  enum analogous to `java.util.stream.Collector.Characteristics` could be used.
+  Out of the box JDK and Guava collection factory methods could be classified,
+  with the user having the option to extend the classification.
+- Refaster currently unconditionally ignores expressions containing comments.
+  Provide two additional modes: (a) match and drop the comments or (b)
+  transport the comments to before/after the replaced expression.
+- Extend Refaster to drop imports that come become unnecessary as a result of a
+  refactoring. This e.g. allows one to replace a statically import TestNG
+  `fail(...)` invocation with a statically imported equivalent AssertJ
+  `fail(...)` invocation. (Observe that without an impor cleanup this
+  replacement would cause a compilation error.)
+- Extend the `@Repeated` match semantics such that it also covers non-varargs
+  methods. For a motivating example see google/error-prone#568.
+- When matching explicit type references, also match super types. For a
+  motivating example, see the two subtly difference loop definitions in
+  `CollectionRemoveAllFromCollectionBlock`.
+- Figure out why Refaster sometimes doesn't match the correct generic overload.
+  See the `AssertThatIterableHasOneComparableElementEqualTo` template for an
+  example.
+
 [autorefactor]: https://autorefactor.org
 [bettercodehub]: https://bettercodehub.com
 [checkstyle-external-project-tests]: https://github.com/checkstyle/checkstyle/blob/master/wercker.yml
 [codecov]: https://codecov.io
-[error-prone-bug-patterns]: http://errorprone.info/bugpatterns
-[error-prone-criteria]: http://errorprone.info/docs/criteria
+[error-prone-bug-patterns]: https://errorprone.info/bugpatterns
+[error-prone-criteria]: https://errorprone.info/docs/criteria
 [error-prone-fork-jitpack]: https://jitpack.io/#PicnicSupermarket/error-prone
 [error-prone-fork-repo]: https://github.com/PicnicSupermarket/error-prone
-[error-prone]: http://errorprone.info
-[error-prone-issue-1239]: https://github.com/google/error-prone/pull/1239
+[error-prone]: https://errorprone.info
 [error-prone-repo]: https://github.com/google/error-prone
 [forbidden-apis]: https://github.com/policeman-tools/forbidden-apis
 [fossa]: https://fossa.io
+[google-java-format]: https://github.com/google/google-java-format
 [maven]: https://maven.apache.org
 [modernizer-maven-plugin]: https://github.com/gaul/modernizer-maven-plugin
 [sonarcloud]: https://sonarcloud.io
+[pitest]: https://pitest.org
+[pitest-maven]: https://pitest.org/quickstart/maven

error-prone-contrib/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.0.1-SNAPSHOT</version>
+        <version>0.1.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>error-prone-contrib</artifactId>
@@ -41,17 +41,24 @@
         </dependency>
         <dependency>
             <groupId>${project.groupId}</groupId>
-            <artifactId>refaster-resource-compiler</artifactId>
-            <!-- This dependency is declared only as a hint to Maven that
-            compilation depends on it; see the `maven-compiler-plugin`'s
-            `annotationProcessorPaths` configuration below. -->
+            <artifactId>refaster-support</artifactId>
             <scope>provided</scope>
         </dependency>
+        <dependency>
+            <groupId>${project.groupId}</groupId>
+            <artifactId>refaster-test-support</artifactId>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-annotations</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>com.google.auto</groupId>
+            <artifactId>auto-common</artifactId>
+            <scope>provided</scope>
+        </dependency>
         <dependency>
             <groupId>com.google.auto.service</groupId>
             <artifactId>auto-service-annotations</artifactId>
@@ -67,11 +74,20 @@
             <artifactId>javac</artifactId>
             <scope>provided</scope>
         </dependency>
+        <dependency>
+            <groupId>com.google.googlejavaformat</groupId>
+            <artifactId>google-java-format</artifactId>
+        </dependency>
         <dependency>
             <groupId>com.google.guava</groupId>
             <artifactId>guava</artifactId>
             <scope>provided</scope>
         </dependency>
+        <dependency>
+            <groupId>com.newrelic.agent.java</groupId>
+            <artifactId>newrelic-api</artifactId>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>io.projectreactor</groupId>
             <artifactId>reactor-core</artifactId>
@@ -97,16 +113,41 @@
             <artifactId>swagger-annotations</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>io.swagger.core.v3</groupId>
+            <artifactId>swagger-annotations</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>jakarta.servlet</groupId>
+            <artifactId>jakarta.servlet-api</artifactId>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>javax.xml.bind</groupId>
             <artifactId>jaxb-api</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.aspectj</groupId>
+            <artifactId>aspectjweaver</artifactId>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>org.assertj</groupId>
             <artifactId>assertj-core</artifactId>
             <scope>provided</scope>
         </dependency>
+        <dependency>
+            <groupId>org.immutables</groupId>
+            <artifactId>value-annotations</artifactId>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-api</artifactId>
@@ -120,7 +161,12 @@
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-params</artifactId>
-            <scope>test</scope>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <scope>provided</scope>
         </dependency>
         <dependency>
             <groupId>org.reactivestreams</groupId>
@@ -134,13 +180,23 @@
         </dependency>
         <dependency>
             <groupId>org.springframework</groupId>
-            <artifactId>spring-beans</artifactId>
-            <scope>test</scope>
+            <artifactId>spring-test</artifactId>
+            <scope>provided</scope>
         </dependency>
         <dependency>
             <groupId>org.springframework</groupId>
             <artifactId>spring-web</artifactId>
-            <scope>test</scope>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-webflux</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-test</artifactId>
+            <scope>provided</scope>
         </dependency>
         <dependency>
             <groupId>org.testng</groupId>
@@ -152,15 +208,6 @@
     <build>
         <pluginManagement>
             <plugins>
-                <plugin>
-                    <groupId>com.coveo</groupId>
-                    <artifactId>fmt-maven-plugin</artifactId>
-                    <configuration>
-                        <additionalSourceDirectories>
-                            <additionalSourceDirectory>${basedir}/src/test/resources</additionalSourceDirectory>
-                        </additionalSourceDirectories>
-                    </configuration>
-                </plugin>
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-compiler-plugin</artifactId>
@@ -168,15 +215,31 @@
                         <annotationProcessorPaths combine.children="append">
                             <path>
                                 <groupId>${project.groupId}</groupId>
-                                <artifactId>refaster-resource-compiler</artifactId>
+                                <artifactId>refaster-compiler</artifactId>
+                                <version>${project.version}</version>
+                            </path>
+                            <path>
+                                <groupId>${project.groupId}</groupId>
+                                <artifactId>refaster-support</artifactId>
                                 <version>${project.version}</version>
                             </path>
                         </annotationProcessorPaths>
                         <compilerArgs combine.children="append">
-                            <arg>-Xplugin:RefasterRuleResourceCompiler</arg>
+                            <arg>-Xplugin:RefasterRuleCompiler</arg>
                         </compilerArgs>
                     </configuration>
                 </plugin>
+                <plugin>
+                    <groupId>org.apache.maven.plugins</groupId>
+                    <artifactId>maven-dependency-plugin</artifactId>
+                    <configuration>
+                        <ignoredUnusedDeclaredDependencies>
+                            <!-- XXX: Figure out why the plugin thinks this
+                            dependency is unused. -->
+                            <ignoredUnusedDeclaredDependency>${project.groupId}:refaster-support</ignoredUnusedDeclaredDependency>
+                        </ignoredUnusedDeclaredDependencies>
+                    </configuration>
+                </plugin>
             </plugins>
         </pluginManagement>
     </build>

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/AmbiguousJsonCreator.java

@@ -0,0 +1,67 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
+import static com.google.errorprone.BugPattern.StandardTags.LIKELY_ERROR;
+import static com.google.errorprone.matchers.Matchers.isType;
+
+import com.google.auto.service.AutoService;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.AnnotationTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.google.errorprone.util.ASTHelpers;
+import com.sun.source.tree.AnnotationTree;
+import com.sun.source.tree.ClassTree;
+import com.sun.source.tree.MethodTree;
+import com.sun.source.tree.Tree;
+import com.sun.tools.javac.code.Symbol;
+import java.util.Map;
+import javax.lang.model.element.AnnotationValue;
+
+/** A {@link BugChecker} which flags ambiguous {@code @JsonCreator}s in enums. */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "`JsonCreator.Mode` should be set for single-argument creators",
+    linkType = NONE,
+    severity = WARNING,
+    tags = LIKELY_ERROR)
+public final class AmbiguousJsonCreator extends BugChecker implements AnnotationTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Matcher<AnnotationTree> IS_JSON_CREATOR_ANNOTATION =
+      isType("com.fasterxml.jackson.annotation.JsonCreator");
+
+  @Override
+  public Description matchAnnotation(AnnotationTree tree, VisitorState state) {
+    if (!IS_JSON_CREATOR_ANNOTATION.matches(tree, state)) {
+      return Description.NO_MATCH;
+    }
+
+    ClassTree clazz = state.findEnclosing(ClassTree.class);
+    if (clazz == null || clazz.getKind() != Tree.Kind.ENUM) {
+      return Description.NO_MATCH;
+    }
+
+    MethodTree method = state.findEnclosing(MethodTree.class);
+    if (method == null || method.getParameters().size() != 1) {
+      return Description.NO_MATCH;
+    }
+
+    boolean customMode =
+        ASTHelpers.getAnnotationMirror(tree).getElementValues().entrySet().stream()
+            .filter(entry -> entry.getKey().getSimpleName().contentEquals("mode"))
+            .map(Map.Entry::getValue)
+            .map(AnnotationValue::getValue)
+            .filter(Symbol.VarSymbol.class::isInstance)
+            .map(Symbol.VarSymbol.class::cast)
+            .anyMatch(varSymbol -> !varSymbol.getSimpleName().contentEquals("DEFAULT"));
+
+    return customMode
+        ? Description.NO_MATCH
+        : describeMatch(
+            tree, SuggestedFix.replace(tree, "@JsonCreator(mode = JsonCreator.Mode.DELEGATING)"));
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/AssertJIsNull.java

@@ -0,0 +1,57 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+import static com.google.errorprone.matchers.Matchers.allOf;
+import static com.google.errorprone.matchers.Matchers.argument;
+import static com.google.errorprone.matchers.Matchers.argumentCount;
+import static com.google.errorprone.matchers.Matchers.instanceMethod;
+import static com.google.errorprone.matchers.Matchers.nullLiteral;
+
+import com.google.auto.service.AutoService;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.fixes.SuggestedFixes;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.sun.source.tree.MethodInvocationTree;
+
+/**
+ * A {@link BugChecker} which flags AssertJ {@code isEqualTo(null)} checks for simplification.
+ *
+ * <p>This bug checker cannot be replaced with a simple Refaster template, as the Refaster approach
+ * would require that all overloads of {@link org.assertj.core.api.Assert#isEqualTo(Object)} (such
+ * as {@link org.assertj.core.api.AbstractStringAssert#isEqualTo(String)}) are explicitly
+ * enumerated. This bug checker generically matches all such current and future overloads.
+ */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "Prefer `.isNull()` over `.isEqualTo(null)`",
+    linkType = NONE,
+    severity = SUGGESTION,
+    tags = SIMPLIFICATION)
+public final class AssertJIsNull extends BugChecker implements MethodInvocationTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Matcher<MethodInvocationTree> ASSERT_IS_EQUAL_TO_NULL =
+      allOf(
+          instanceMethod().onDescendantOf("org.assertj.core.api.Assert").named("isEqualTo"),
+          argumentCount(1),
+          argument(0, nullLiteral()));
+
+  @Override
+  public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    if (!ASSERT_IS_EQUAL_TO_NULL.matches(tree, state)) {
+      return Description.NO_MATCH;
+    }
+
+    SuggestedFix.Builder fix =
+        SuggestedFix.builder().merge(SuggestedFixes.renameMethodInvocation(tree, "isNull", state));
+    tree.getArguments().forEach(arg -> fix.merge(SuggestedFix.delete(arg)));
+
+    return describeMatch(tree, fix.build());
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/AutowiredConstructor.java

@@ -0,0 +1,62 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+import static com.google.errorprone.matchers.ChildMultiMatcher.MatchType.AT_LEAST_ONE;
+import static com.google.errorprone.matchers.Matchers.annotations;
+import static com.google.errorprone.matchers.Matchers.isType;
+
+import com.google.auto.service.AutoService;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Iterables;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.ClassTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.MultiMatcher;
+import com.google.errorprone.util.ASTHelpers;
+import com.sun.source.tree.AnnotationTree;
+import com.sun.source.tree.ClassTree;
+import com.sun.source.tree.MethodTree;
+import com.sun.source.tree.Tree;
+import java.util.List;
+
+/** A {@link BugChecker} which flags redundant {@code @Autowired} constructor annotations. */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "Omit `@Autowired` on a class' sole constructor, as it is redundant",
+    linkType = NONE,
+    severity = SUGGESTION,
+    tags = SIMPLIFICATION)
+public final class AutowiredConstructor extends BugChecker implements ClassTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final MultiMatcher<Tree, AnnotationTree> AUTOWIRED_ANNOTATION =
+      annotations(AT_LEAST_ONE, isType("org.springframework.beans.factory.annotation.Autowired"));
+
+  @Override
+  public Description matchClass(ClassTree tree, VisitorState state) {
+    List<MethodTree> constructors = ASTHelpers.getConstructors(tree);
+    if (constructors.size() != 1) {
+      return Description.NO_MATCH;
+    }
+
+    ImmutableList<AnnotationTree> annotations =
+        AUTOWIRED_ANNOTATION
+            .multiMatchResult(Iterables.getOnlyElement(constructors), state)
+            .matchingNodes();
+    if (annotations.size() != 1) {
+      return Description.NO_MATCH;
+    }
+
+    /*
+     * This is the only `@Autowired` constructor: suggest that it be removed. Note that this likely
+     * means that the associated import can be removed as well. Rather than adding code for this case we
+     * leave flagging the unused import to Error Prone's `RemoveUnusedImports` check.
+     */
+    AnnotationTree annotation = Iterables.getOnlyElement(annotations);
+    return describeMatch(annotation, SuggestedFix.delete(annotation));
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/AutowiredConstructorCheck.java

@@ -1,68 +0,0 @@
-package tech.picnic.errorprone.bugpatterns;
-
-import com.google.auto.service.AutoService;
-import com.google.errorprone.BugPattern;
-import com.google.errorprone.BugPattern.LinkType;
-import com.google.errorprone.BugPattern.ProvidesFix;
-import com.google.errorprone.BugPattern.SeverityLevel;
-import com.google.errorprone.BugPattern.StandardTags;
-import com.google.errorprone.VisitorState;
-import com.google.errorprone.bugpatterns.BugChecker;
-import com.google.errorprone.bugpatterns.BugChecker.AnnotationTreeMatcher;
-import com.google.errorprone.fixes.SuggestedFix;
-import com.google.errorprone.matchers.AnnotationType;
-import com.google.errorprone.matchers.Description;
-import com.google.errorprone.matchers.Matcher;
-import com.google.errorprone.util.ASTHelpers;
-import com.sun.source.tree.AnnotationTree;
-import com.sun.source.tree.ClassTree;
-import com.sun.source.tree.MethodTree;
-import com.sun.tools.javac.code.Symbol.MethodSymbol;
-
-/** A {@link BugChecker} which flags redundant {@code @Autowired} constructor annotations. */
-@AutoService(BugChecker.class)
-@BugPattern(
-    name = "AutowiredConstructor",
-    summary = "Omit `@Autowired` on a class' sole constructor, as it is redundant",
-    linkType = LinkType.NONE,
-    severity = SeverityLevel.SUGGESTION,
-    tags = StandardTags.SIMPLIFICATION,
-    providesFix = ProvidesFix.REQUIRES_HUMAN_ATTENTION)
-public final class AutowiredConstructorCheck extends BugChecker implements AnnotationTreeMatcher {
-  private static final long serialVersionUID = 1L;
-  private static final Matcher<AnnotationTree> AUTOWIRED_ANNOTATION =
-      new AnnotationType("org.springframework.beans.factory.annotation.Autowired");
-
-  @Override
-  public Description matchAnnotation(AnnotationTree tree, VisitorState state) {
-    if (!AUTOWIRED_ANNOTATION.matches(tree, state)) {
-      return Description.NO_MATCH;
-    }
-
-    if (!isWithinConstructor(state)) {
-      return Description.NO_MATCH;
-    }
-
-    ClassTree clazz = state.findEnclosing(ClassTree.class);
-    if (clazz == null || ASTHelpers.getConstructors(clazz).size() != 1) {
-      return Description.NO_MATCH;
-    }
-
-    /*
-     * This is the only `@Autowired` constructor: suggest that it be removed. Note that this likely
-     * means that the associated import can be removed as well. Rather than adding code for this case we
-     * leave flagging the unused import to Error Prone's `RemoveUnusedImports` check.
-     */
-    return describeMatch(tree, SuggestedFix.delete(tree));
-  }
-
-  private static boolean isWithinConstructor(VisitorState state) {
-    MethodTree method = state.findEnclosing(MethodTree.class);
-    if (method == null) {
-      return false;
-    }
-
-    MethodSymbol sym = ASTHelpers.getSymbol(method);
-    return sym != null && sym.isConstructor();
-  }
-}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/CanonicalAnnotationSyntax.java

@@ -1,22 +1,22 @@
 package tech.picnic.errorprone.bugpatterns;
 
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+
 import com.google.auto.service.AutoService;
 import com.google.common.collect.ImmutableSet;
 import com.google.errorprone.BugPattern;
-import com.google.errorprone.BugPattern.LinkType;
-import com.google.errorprone.BugPattern.ProvidesFix;
-import com.google.errorprone.BugPattern.SeverityLevel;
-import com.google.errorprone.BugPattern.StandardTags;
 import com.google.errorprone.VisitorState;
 import com.google.errorprone.bugpatterns.BugChecker;
 import com.google.errorprone.bugpatterns.BugChecker.AnnotationTreeMatcher;
 import com.google.errorprone.fixes.Fix;
 import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.matchers.AnnotationMatcherUtils;
 import com.google.errorprone.matchers.Description;
 import com.sun.source.tree.AnnotationTree;
 import com.sun.source.tree.AssignmentTree;
 import com.sun.source.tree.ExpressionTree;
-import com.sun.source.tree.IdentifierTree;
 import com.sun.source.tree.NewArrayTree;
 import com.sun.source.tree.Tree.Kind;
 import java.util.ArrayList;
@@ -25,26 +25,24 @@ import java.util.Optional;
 import java.util.function.BiFunction;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
+import tech.picnic.errorprone.bugpatterns.util.SourceCode;
 
 /** A {@link BugChecker} which flags annotations that could be written more concisely. */
 @AutoService(BugChecker.class)
 @BugPattern(
-    name = "CanonicalAnnotationSyntax",
     summary = "Omit redundant syntax from annotation declarations",
-    linkType = LinkType.NONE,
-    severity = SeverityLevel.SUGGESTION,
-    tags = StandardTags.SIMPLIFICATION,
-    providesFix = ProvidesFix.REQUIRES_HUMAN_ATTENTION)
-public final class CanonicalAnnotationSyntaxCheck extends BugChecker
-    implements AnnotationTreeMatcher {
+    linkType = NONE,
+    severity = SUGGESTION,
+    tags = SIMPLIFICATION)
+public final class CanonicalAnnotationSyntax extends BugChecker implements AnnotationTreeMatcher {
   private static final long serialVersionUID = 1L;
   private static final Pattern TRAILING_ARRAY_COMMA = Pattern.compile(",\\s*}$");
   private static final ImmutableSet<BiFunction<AnnotationTree, VisitorState, Optional<Fix>>>
       FIX_FACTORIES =
           ImmutableSet.of(
-              CanonicalAnnotationSyntaxCheck::dropRedundantParentheses,
-              CanonicalAnnotationSyntaxCheck::dropRedundantValueAttribute,
-              CanonicalAnnotationSyntaxCheck::dropRedundantCurlies);
+              CanonicalAnnotationSyntax::dropRedundantParentheses,
+              CanonicalAnnotationSyntax::dropRedundantValueAttribute,
+              CanonicalAnnotationSyntax::dropRedundantCurlies);
 
   @Override
   public Description matchAnnotation(AnnotationTree tree, VisitorState state) {
@@ -86,26 +84,26 @@ public final class CanonicalAnnotationSyntaxCheck extends BugChecker
     }
 
     ExpressionTree arg = args.get(0);
-    if (arg.getKind() != Kind.ASSIGNMENT) {
-      /* Evidently `value` isn't assigned to explicitly. */
+    if (state.getSourceForNode(arg) == null) {
+      /*
+       * The annotation argument isn't doesn't have a source representation, e.g. because `value`
+       * isn't assigned to explicitly.
+       */
       return Optional.empty();
     }
 
-    AssignmentTree assignment = (AssignmentTree) arg;
-    ExpressionTree variable = assignment.getVariable();
-    if (variable.getKind() != Kind.IDENTIFIER
-        || !((IdentifierTree) variable).getName().contentEquals("value")
-        || state.getSourceForNode(variable) == null) {
+    ExpressionTree expr = AnnotationMatcherUtils.getArgument(tree, "value");
+    if (expr == null) {
       /* This is not an explicit assignment to the `value` attribute. */
       return Optional.empty();
     }
 
     /* Replace the assignment with (the simplified representation of) just its value. */
-    ExpressionTree expr = assignment.getExpression();
     return Optional.of(
         SuggestedFix.replace(
             arg,
-            simplifyAttributeValue(expr, state).orElseGet(() -> Util.treeToString(expr, state))));
+            simplifyAttributeValue(expr, state)
+                .orElseGet(() -> SourceCode.treeToString(expr, state))));
   }
 
   private static Optional<Fix> dropRedundantCurlies(AnnotationTree tree, VisitorState state) {
@@ -140,11 +138,11 @@ public final class CanonicalAnnotationSyntaxCheck extends BugChecker
   private static Optional<String> simplifySingletonArray(NewArrayTree array, VisitorState state) {
     return Optional.of(array.getInitializers())
         .filter(initializers -> initializers.size() == 1)
-        .map(initializers -> Util.treeToString(initializers.get(0), state));
+        .map(initializers -> SourceCode.treeToString(initializers.get(0), state));
   }
 
   private static Optional<String> dropTrailingComma(NewArrayTree array, VisitorState state) {
-    String src = Util.treeToString(array, state);
+    String src = SourceCode.treeToString(array, state);
     return Optional.of(TRAILING_ARRAY_COMMA.matcher(src))
         .filter(Matcher::find)
         .map(m -> src.substring(0, m.start()) + '}');

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/CollectorMutability.java

@@ -0,0 +1,117 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
+import static com.google.errorprone.BugPattern.StandardTags.FRAGILE_CODE;
+import static com.google.errorprone.matchers.method.MethodMatchers.staticMethod;
+
+import com.google.auto.service.AutoService;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.fixes.SuggestedFixes;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.MethodInvocationTree;
+import java.util.stream.Collector;
+
+/**
+ * A {@link BugChecker} which flags {@link Collector Collectors} that don't clearly express
+ * (im)mutability.
+ *
+ * <p>Replacing such collectors with alternatives that produce immutable collections is preferred.
+ * Do note that Guava's immutable collections are null-hostile.
+ */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary =
+        "Avoid `Collectors.to{List,Map,Set}` in favour of alternatives that emphasize (im)mutability",
+    linkType = NONE,
+    severity = WARNING,
+    tags = FRAGILE_CODE)
+public final class CollectorMutability extends BugChecker implements MethodInvocationTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Matcher<ExpressionTree> COLLECTOR_METHOD =
+      staticMethod().onClass("java.util.stream.Collectors");
+  private static final Matcher<ExpressionTree> LIST_COLLECTOR =
+      staticMethod().anyClass().named("toList");
+  private static final Matcher<ExpressionTree> MAP_COLLECTOR =
+      staticMethod().anyClass().named("toMap");
+  private static final Matcher<ExpressionTree> SET_COLLECTOR =
+      staticMethod().anyClass().named("toSet");
+
+  @Override
+  public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    if (!COLLECTOR_METHOD.matches(tree, state)) {
+      return Description.NO_MATCH;
+    }
+
+    if (LIST_COLLECTOR.matches(tree, state)) {
+      return suggestToCollectionAlternatives(
+          tree, "com.google.common.collect.ImmutableList.toImmutableList", "ArrayList", state);
+    }
+
+    if (MAP_COLLECTOR.matches(tree, state)) {
+      return suggestToMapAlternatives(tree, state);
+    }
+
+    if (SET_COLLECTOR.matches(tree, state)) {
+      return suggestToCollectionAlternatives(
+          tree, "com.google.common.collect.ImmutableSet.toImmutableSet", "HashSet", state);
+    }
+
+    return Description.NO_MATCH;
+  }
+
+  private Description suggestToCollectionAlternatives(
+      MethodInvocationTree tree,
+      String fullyQualifiedImmutableReplacement,
+      String mutableReplacement,
+      VisitorState state) {
+    SuggestedFix.Builder mutableFix = SuggestedFix.builder();
+    String toCollectionSelect =
+        SuggestedFixes.qualifyStaticImport(
+            "java.util.stream.Collectors.toCollection", mutableFix, state);
+
+    return buildDescription(tree)
+        .addFix(replaceMethodInvocation(tree, fullyQualifiedImmutableReplacement, state))
+        .addFix(
+            mutableFix
+                .addImport(String.format("java.util.%s", mutableReplacement))
+                .replace(tree, String.format("%s(%s::new)", toCollectionSelect, mutableReplacement))
+                .build())
+        .build();
+  }
+
+  private Description suggestToMapAlternatives(MethodInvocationTree tree, VisitorState state) {
+    int argCount = tree.getArguments().size();
+    if (argCount > 3) {
+      return Description.NO_MATCH;
+    }
+
+    return buildDescription(tree)
+        .addFix(
+            replaceMethodInvocation(
+                tree, "com.google.common.collect.ImmutableMap.toImmutableMap", state))
+        .addFix(
+            SuggestedFix.builder()
+                .addImport("java.util.HashMap")
+                .postfixWith(
+                    tree.getArguments().get(argCount - 1),
+                    (argCount == 2 ? ", (a, b) -> { throw new IllegalStateException(); }" : "")
+                        + ", HashMap::new")
+                .build())
+        .build();
+  }
+
+  private static SuggestedFix replaceMethodInvocation(
+      MethodInvocationTree tree, String fullyQualifiedReplacement, VisitorState state) {
+    SuggestedFix.Builder fix = SuggestedFix.builder();
+    String replacement = SuggestedFixes.qualifyStaticImport(fullyQualifiedReplacement, fix, state);
+    fix.merge(SuggestedFix.replace(tree.getMethodSelect(), replacement));
+    return fix.build();
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/EmptyMethod.java

@@ -0,0 +1,62 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+import static com.google.errorprone.matchers.ChildMultiMatcher.MatchType.AT_LEAST_ONE;
+import static com.google.errorprone.matchers.Matchers.annotations;
+import static com.google.errorprone.matchers.Matchers.anyOf;
+import static com.google.errorprone.matchers.Matchers.isType;
+
+import com.google.auto.service.AutoService;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.google.errorprone.util.ASTHelpers;
+import com.sun.source.tree.ClassTree;
+import com.sun.source.tree.MethodTree;
+import com.sun.source.tree.Tree;
+import java.util.Optional;
+
+/** A {@link BugChecker} which flags empty methods that seemingly can simply be deleted. */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "Empty method can likely be deleted",
+    linkType = NONE,
+    severity = SUGGESTION,
+    tags = SIMPLIFICATION)
+public final class EmptyMethod extends BugChecker implements MethodTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Matcher<Tree> PERMITTED_ANNOTATION =
+      annotations(
+          AT_LEAST_ONE,
+          anyOf(isType("java.lang.Override"), isType("org.aspectj.lang.annotation.Pointcut")));
+
+  @Override
+  public Description matchMethod(MethodTree tree, VisitorState state) {
+    if (tree.getBody() == null
+        || !tree.getBody().getStatements().isEmpty()
+        || ASTHelpers.containsComments(tree, state)
+        || PERMITTED_ANNOTATION.matches(tree, state)
+        || isInPossibleTestHelperClass(state)) {
+      return Description.NO_MATCH;
+    }
+
+    if (ASTHelpers.methodCanBeOverridden(ASTHelpers.getSymbol(tree))) {
+      return Description.NO_MATCH;
+    }
+
+    return describeMatch(tree, SuggestedFix.delete(tree));
+  }
+
+  private static boolean isInPossibleTestHelperClass(VisitorState state) {
+    return Optional.ofNullable(ASTHelpers.findEnclosingNode(state.getPath(), ClassTree.class))
+        .map(ClassTree::getSimpleName)
+        .filter(name -> name.toString().contains("Test"))
+        .isPresent();
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/EmptyMethodCheck.java

@@ -1,44 +0,0 @@
-package tech.picnic.errorprone.bugpatterns;
-
-import com.google.auto.service.AutoService;
-import com.google.errorprone.BugPattern;
-import com.google.errorprone.BugPattern.LinkType;
-import com.google.errorprone.BugPattern.SeverityLevel;
-import com.google.errorprone.BugPattern.StandardTags;
-import com.google.errorprone.VisitorState;
-import com.google.errorprone.bugpatterns.BugChecker;
-import com.google.errorprone.bugpatterns.BugChecker.MethodTreeMatcher;
-import com.google.errorprone.fixes.SuggestedFix;
-import com.google.errorprone.matchers.Description;
-import com.google.errorprone.util.ASTHelpers;
-import com.sun.source.tree.MethodTree;
-import com.sun.tools.javac.code.Symbol.MethodSymbol;
-
-/** A {@link BugChecker} which flags empty methods that seemingly can simply be deleted. */
-@AutoService(BugChecker.class)
-@BugPattern(
-    name = "EmptyMethod",
-    summary = "Empty method can likely be deleted",
-    linkType = LinkType.NONE,
-    severity = SeverityLevel.WARNING,
-    tags = StandardTags.SIMPLIFICATION,
-    providesFix = BugPattern.ProvidesFix.REQUIRES_HUMAN_ATTENTION)
-public final class EmptyMethodCheck extends BugChecker implements MethodTreeMatcher {
-  private static final long serialVersionUID = 1L;
-
-  @Override
-  public Description matchMethod(MethodTree tree, VisitorState state) {
-    if (tree.getBody() == null || !tree.getBody().getStatements().isEmpty()) {
-      return Description.NO_MATCH;
-    }
-
-    MethodSymbol sym = ASTHelpers.getSymbol(tree);
-    if (sym == null
-        || ASTHelpers.methodCanBeOverridden(sym)
-        || ASTHelpers.hasAnnotation(sym, "java.lang.Override", state)) {
-      return Description.NO_MATCH;
-    }
-
-    return describeMatch(tree, SuggestedFix.delete(tree));
-  }
-}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/ErrorProneTestHelperSourceFormat.java

@@ -0,0 +1,160 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static com.google.errorprone.BugPattern.StandardTags.STYLE;
+import static com.google.errorprone.matchers.Matchers.anyOf;
+import static com.google.errorprone.matchers.Matchers.instanceMethod;
+import static java.util.stream.Collectors.joining;
+
+import com.google.auto.service.AutoService;
+import com.google.common.base.Splitter;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.google.errorprone.util.ASTHelpers;
+import com.google.googlejavaformat.java.Formatter;
+import com.google.googlejavaformat.java.FormatterException;
+import com.google.googlejavaformat.java.ImportOrderer;
+import com.google.googlejavaformat.java.JavaFormatterOptions.Style;
+import com.google.googlejavaformat.java.RemoveUnusedImports;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.MethodInvocationTree;
+import com.sun.source.tree.Tree;
+import com.sun.tools.javac.util.Position;
+import java.util.List;
+import java.util.Optional;
+
+/**
+ * A {@link BugChecker} which flags improperly formatted Error Prone test code.
+ *
+ * <p>All test code should be formatted in accordance with Google Java Format's {@link Formatter}
+ * output, and imports should be ordered according to the {@link Style#GOOGLE Google} style.
+ *
+ * <p>This checker inspects inline code passed to {@code
+ * com.google.errorprone.CompilationTestHelper} and {@code
+ * com.google.errorprone.BugCheckerRefactoringTestHelper}. It requires that this code is properly
+ * formatted and that its imports are organized. Only code that represents the expected output of a
+ * refactoring operation is allowed to have unused imports, as most {@link BugChecker}s do not (and
+ * are not able to) remove imports that become obsolete as a result of applying their suggested
+ * fix(es).
+ */
+// XXX: Once we target JDK 17 (optionally?) suggest text block fixes.
+// XXX: GJF guesses the line separator to be used by inspecting the source. When using text blocks
+// this may cause the current unconditional use of `\n` not to be sufficient when building on
+// Windows; TBD.
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "Test code should follow the Google Java style",
+    linkType = NONE,
+    severity = SUGGESTION,
+    tags = STYLE)
+public final class ErrorProneTestHelperSourceFormat extends BugChecker
+    implements MethodInvocationTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Formatter FORMATTER = new Formatter();
+  private static final Matcher<ExpressionTree> INPUT_SOURCE_ACCEPTING_METHOD =
+      anyOf(
+          instanceMethod()
+              .onDescendantOf("com.google.errorprone.CompilationTestHelper")
+              .named("addSourceLines"),
+          instanceMethod()
+              .onDescendantOf("com.google.errorprone.BugCheckerRefactoringTestHelper")
+              .named("addInputLines"));
+  private static final Matcher<ExpressionTree> OUTPUT_SOURCE_ACCEPTING_METHOD =
+      instanceMethod()
+          .onDescendantOf("com.google.errorprone.BugCheckerRefactoringTestHelper.ExpectOutput")
+          .named("addOutputLines");
+
+  @Override
+  public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    boolean isOutputSource = OUTPUT_SOURCE_ACCEPTING_METHOD.matches(tree, state);
+    if (!isOutputSource && !INPUT_SOURCE_ACCEPTING_METHOD.matches(tree, state)) {
+      return Description.NO_MATCH;
+    }
+
+    List<? extends ExpressionTree> sourceLines =
+        tree.getArguments().subList(1, tree.getArguments().size());
+    if (sourceLines.isEmpty()) {
+      return buildDescription(tree).setMessage("No source code provided").build();
+    }
+
+    int startPos = ASTHelpers.getStartPosition(sourceLines.get(0));
+    int endPos = state.getEndPosition(sourceLines.get(sourceLines.size() - 1));
+
+    /* Attempt to format the source code only if it fully consists of constant expressions. */
+    return getConstantSourceCode(sourceLines)
+        .map(source -> flagFormattingIssues(startPos, endPos, source, isOutputSource, state))
+        .orElse(Description.NO_MATCH);
+  }
+
+  private Description flagFormattingIssues(
+      int startPos, int endPos, String source, boolean retainUnusedImports, VisitorState state) {
+    Tree methodInvocation = state.getPath().getLeaf();
+
+    String formatted;
+    try {
+      formatted = formatSourceCode(source, retainUnusedImports).trim();
+    } catch (FormatterException e) {
+      return buildDescription(methodInvocation)
+          .setMessage(String.format("Source code is malformed: %s", e.getMessage()))
+          .build();
+    }
+
+    if (source.trim().equals(formatted)) {
+      return Description.NO_MATCH;
+    }
+
+    if (startPos == Position.NOPOS || endPos == Position.NOPOS) {
+      /*
+       * We have insufficient source information to emit a fix, so we only flag the fact that the
+       * code isn't properly formatted.
+       */
+      return describeMatch(methodInvocation);
+    }
+
+    /*
+     * The code isn't properly formatted; replace all lines with the properly formatted
+     * alternatives.
+     */
+    return describeMatch(
+        methodInvocation,
+        SuggestedFix.replace(
+            startPos,
+            endPos,
+            Splitter.on('\n')
+                .splitToStream(formatted)
+                .map(state::getConstantExpression)
+                .collect(joining(", "))));
+  }
+
+  private static String formatSourceCode(String source, boolean retainUnusedImports)
+      throws FormatterException {
+    String withReorderedImports = ImportOrderer.reorderImports(source, Style.GOOGLE);
+    String withOptionallyRemovedImports =
+        retainUnusedImports
+            ? withReorderedImports
+            : RemoveUnusedImports.removeUnusedImports(withReorderedImports);
+    return FORMATTER.formatSource(withOptionallyRemovedImports);
+  }
+
+  private static Optional<String> getConstantSourceCode(
+      List<? extends ExpressionTree> sourceLines) {
+    StringBuilder source = new StringBuilder();
+
+    for (ExpressionTree sourceLine : sourceLines) {
+      Object value = ASTHelpers.constValue(sourceLine);
+      if (value == null) {
+        return Optional.empty();
+      }
+
+      source.append(value).append('\n');
+    }
+
+    return Optional.of(source.toString());
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/ExplicitEnumOrdering.java

@@ -0,0 +1,89 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.common.collect.ImmutableSet.toImmutableSet;
+import static com.google.common.collect.ImmutableSetMultimap.toImmutableSetMultimap;
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
+import static com.google.errorprone.BugPattern.StandardTags.FRAGILE_CODE;
+import static com.google.errorprone.matchers.method.MethodMatchers.staticMethod;
+import static java.util.stream.Collectors.collectingAndThen;
+
+import com.google.auto.service.AutoService;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.ImmutableSetMultimap;
+import com.google.common.collect.Multimaps;
+import com.google.common.collect.Ordering;
+import com.google.common.collect.Sets;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.google.errorprone.util.ASTHelpers;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.MethodInvocationTree;
+import com.sun.tools.javac.code.Symbol;
+import com.sun.tools.javac.code.Type;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Stream;
+
+/**
+ * A {@link BugChecker} which flags {@link Ordering#explicit(Object, Object[])}} invocations listing
+ * a subset of an enum type's values.
+ */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "Make sure `Ordering#explicit` lists all of an enum's values",
+    linkType = NONE,
+    severity = WARNING,
+    tags = FRAGILE_CODE)
+public final class ExplicitEnumOrdering extends BugChecker implements MethodInvocationTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Matcher<ExpressionTree> EXPLICIT_ORDERING =
+      staticMethod().onClass(Ordering.class.getName()).named("explicit");
+
+  @Override
+  public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    if (!EXPLICIT_ORDERING.matches(tree, state)) {
+      return Description.NO_MATCH;
+    }
+
+    ImmutableSet<String> missingEnumValues = getMissingEnumValues(tree.getArguments());
+    if (missingEnumValues.isEmpty()) {
+      return Description.NO_MATCH;
+    }
+
+    return buildDescription(tree)
+        .setMessage(
+            String.format(
+                "Explicit ordering lacks some enum values: %s",
+                String.join(", ", missingEnumValues)))
+        .build();
+  }
+
+  private static ImmutableSet<String> getMissingEnumValues(
+      List<? extends ExpressionTree> expressions) {
+    return expressions.stream()
+        .map(ASTHelpers::getSymbol)
+        .filter(Symbol::isEnum)
+        .collect(
+            collectingAndThen(
+                toImmutableSetMultimap(Symbol::asType, Symbol::toString),
+                ExplicitEnumOrdering::getMissingEnumValues));
+  }
+
+  private static ImmutableSet<String> getMissingEnumValues(
+      ImmutableSetMultimap<Type, String> valuesByType) {
+    return Multimaps.asMap(valuesByType).entrySet().stream()
+        .flatMap(e -> getMissingEnumValues(e.getKey(), e.getValue()))
+        .collect(toImmutableSet());
+  }
+
+  private static Stream<String> getMissingEnumValues(Type enumType, Set<String> values) {
+    Symbol.TypeSymbol typeSymbol = enumType.asElement();
+    return Sets.difference(ASTHelpers.enumValues(typeSymbol), values).stream()
+        .map(v -> String.format("%s.%s", typeSymbol.getSimpleName(), v));
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/FluxFlatMapUsage.java

@@ -0,0 +1,85 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.ERROR;
+import static com.google.errorprone.BugPattern.StandardTags.LIKELY_ERROR;
+import static com.google.errorprone.matchers.method.MethodMatchers.instanceMethod;
+
+import com.google.auto.service.AutoService;
+import com.google.common.collect.Iterables;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MemberReferenceTreeMatcher;
+import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.fixes.SuggestedFixes;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.MemberReferenceTree;
+import com.sun.source.tree.MethodInvocationTree;
+import java.util.function.Function;
+import java.util.function.Supplier;
+import reactor.core.publisher.Flux;
+
+/**
+ * A {@link BugChecker} which flags usages of {@link Flux#flatMap(Function)} and {@link
+ * Flux#flatMapSequential(Function)}.
+ *
+ * <p>{@link Flux#flatMap(Function)} and {@link Flux#flatMapSequential(Function)} eagerly perform up
+ * to {@link reactor.util.concurrent.Queues#SMALL_BUFFER_SIZE} subscriptions. Additionally, the
+ * former interleaves values as they are emitted, yielding nondeterministic results. In most cases
+ * {@link Flux#concatMap(Function)} should be preferred, as it produces consistent results and
+ * avoids potentially saturating the thread pool on which subscription happens. If {@code
+ * concatMap}'s single-subscription semantics are undesirable one should invoke a {@code flatMap} or
+ * {@code flatMapSequential} overload with an explicit concurrency level.
+ *
+ * <p>NB: The rarely-used overload {@link Flux#flatMap(Function, Function, Supplier)} is not flagged
+ * by this check because there is no clear alternative to point to.
+ */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary =
+        "`Flux#flatMap` and `Flux#flatMapSequential` have subtle semantics; "
+            + "please use `Flux#concatMap` or explicitly specify the desired amount of concurrency",
+    linkType = NONE,
+    severity = ERROR,
+    tags = LIKELY_ERROR)
+public final class FluxFlatMapUsage extends BugChecker
+    implements MethodInvocationTreeMatcher, MemberReferenceTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final String MAX_CONCURRENCY_ARG_NAME = "MAX_CONCURRENCY";
+  private static final Matcher<ExpressionTree> FLUX_FLATMAP =
+      instanceMethod()
+          .onDescendantOf("reactor.core.publisher.Flux")
+          .namedAnyOf("flatMap", "flatMapSequential")
+          .withParameters(Function.class.getName());
+
+  @Override
+  public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    if (!FLUX_FLATMAP.matches(tree, state)) {
+      return Description.NO_MATCH;
+    }
+
+    return buildDescription(tree)
+        .addFix(SuggestedFixes.renameMethodInvocation(tree, "concatMap", state))
+        .addFix(
+            SuggestedFix.builder()
+                .postfixWith(
+                    Iterables.getOnlyElement(tree.getArguments()), ", " + MAX_CONCURRENCY_ARG_NAME)
+                .build())
+        .build();
+  }
+
+  @Override
+  public Description matchMemberReference(MemberReferenceTree tree, VisitorState state) {
+    if (!FLUX_FLATMAP.matches(tree, state)) {
+      return Description.NO_MATCH;
+    }
+
+    // Method references are expected to occur very infrequently; generating both variants of
+    // suggested fixes is not worth the trouble.
+    return describeMatch(tree);
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/FormatStringConcatenation.java

@@ -0,0 +1,257 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+import static com.google.errorprone.matchers.Matchers.allOf;
+import static com.google.errorprone.matchers.Matchers.anyMethod;
+import static com.google.errorprone.matchers.Matchers.anyOf;
+import static com.google.errorprone.matchers.Matchers.instanceMethod;
+import static com.google.errorprone.matchers.Matchers.not;
+import static com.google.errorprone.matchers.Matchers.staticMethod;
+import static java.util.stream.Collectors.joining;
+
+import com.google.auto.service.AutoService;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.google.errorprone.util.ASTHelpers;
+import com.sun.source.tree.BinaryTree;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.LiteralTree;
+import com.sun.source.tree.MethodInvocationTree;
+import com.sun.source.tree.ParenthesizedTree;
+import com.sun.source.tree.Tree;
+import com.sun.source.tree.Tree.Kind;
+import com.sun.source.util.SimpleTreeVisitor;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Optional;
+import javax.annotation.Nullable;
+import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+
+/**
+ * A {@link BugChecker} which flags string concatenations that produce a format string; in such
+ * cases the string concatenation should instead be deferred to the invoked method.
+ *
+ * @implNote This checker is based on the implementation of {@link
+ *     com.google.errorprone.bugpatterns.flogger.FloggerStringConcatenation}.
+ */
+// XXX: Support arbitrary `@FormatMethod`-annotated methods.
+// XXX: For (explicit or delegated) invocations of `java.util.Formatter` _strictly speaking_ we
+// should introduce special handling of `Formattable` arguments, as this check would replace a
+// `Formattable#toString` invocation with a `Formattable#formatTo` invocation. But likely that
+// should be considered a bug fix, too.
+// XXX: Introduce a separate check which adds/removes the `Locale` parameter to `String.format`
+// invocations, as necessary.
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "Defer string concatenation to the invoked method",
+    linkType = NONE,
+    severity = WARNING,
+    tags = SIMPLIFICATION)
+public final class FormatStringConcatenation extends BugChecker
+    implements MethodInvocationTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  /**
+   * AssertJ exposes varargs {@code fail} methods with a {@link Throwable}-accepting overload, the
+   * latter of which should not be flagged.
+   */
+  private static final Matcher<ExpressionTree> ASSERTJ_FAIL_WITH_THROWABLE_METHOD =
+      anyMethod()
+          .anyClass()
+          .withAnyName()
+          .withParameters(String.class.getName(), Throwable.class.getName());
+  // XXX: Drop some of these methods if we use Refaster to replace some with others.
+  private static final Matcher<ExpressionTree> ASSERTJ_FORMAT_METHOD =
+      anyOf(
+          instanceMethod()
+              .onDescendantOf("org.assertj.core.api.AbstractAssert")
+              .namedAnyOf("overridingErrorMessage", "withFailMessage"),
+          allOf(
+              instanceMethod()
+                  .onDescendantOf("org.assertj.core.api.AbstractSoftAssertions")
+                  .named("fail"),
+              not(ASSERTJ_FAIL_WITH_THROWABLE_METHOD)),
+          instanceMethod()
+              .onDescendantOf("org.assertj.core.api.AbstractStringAssert")
+              .named("isEqualTo"),
+          instanceMethod()
+              .onDescendantOf("org.assertj.core.api.AbstractThrowableAssert")
+              .namedAnyOf(
+                  "hasMessage",
+                  "hasMessageContaining",
+                  "hasMessageEndingWith",
+                  "hasMessageStartingWith",
+                  "hasRootCauseMessage",
+                  "hasStackTraceContaining"),
+          instanceMethod()
+              .onDescendantOf("org.assertj.core.api.Descriptable")
+              .namedAnyOf("as", "describedAs"),
+          instanceMethod()
+              .onDescendantOf("org.assertj.core.api.ThrowableAssertAlternative")
+              .namedAnyOf(
+                  "withMessage",
+                  "withMessageContaining",
+                  "withMessageEndingWith",
+                  "withMessageStartingWith",
+                  "withStackTraceContaining"),
+          allOf(
+              instanceMethod().onDescendantOf("org.assertj.core.api.WithAssertions").named("fail"),
+              not(ASSERTJ_FAIL_WITH_THROWABLE_METHOD)),
+          allOf(
+              staticMethod()
+                  .onClassAny(
+                      "org.assertj.core.api.Assertions",
+                      "org.assertj.core.api.BDDAssertions",
+                      "org.assertj.core.api.Fail")
+                  .named("fail"),
+              not(ASSERTJ_FAIL_WITH_THROWABLE_METHOD)));
+  private static final Matcher<ExpressionTree> GUAVA_FORMAT_METHOD =
+      anyOf(
+          staticMethod()
+              .onClass("com.google.common.base.Preconditions")
+              .namedAnyOf("checkArgument", "checkNotNull", "checkState"),
+          staticMethod().onClass("com.google.common.base.Verify").named("verify"));
+  // XXX: Add `PrintWriter`, maybe others.
+  private static final Matcher<ExpressionTree> JDK_FORMAT_METHOD =
+      anyOf(
+          staticMethod().onClass("java.lang.String").named("format"),
+          instanceMethod().onExactClass("java.util.Formatter").named("format"));
+  private static final Matcher<ExpressionTree> SLF4J_FORMAT_METHOD =
+      instanceMethod()
+          .onDescendantOf("org.slf4j.Logger")
+          .namedAnyOf("debug", "error", "info", "trace", "warn");
+
+  @Override
+  public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    if (hasNonConstantStringConcatenationArgument(tree, 0, state)) {
+      return flagViolation(tree, ASSERTJ_FORMAT_METHOD, 0, "%s", state)
+          .or(() -> flagViolation(tree, JDK_FORMAT_METHOD, 0, "%s", state))
+          .or(() -> flagViolation(tree, SLF4J_FORMAT_METHOD, 0, "{}", state))
+          .orElse(Description.NO_MATCH);
+    }
+
+    if (hasNonConstantStringConcatenationArgument(tree, 1, state)) {
+      return flagViolation(tree, GUAVA_FORMAT_METHOD, 1, "%s", state)
+          .or(() -> flagViolation(tree, JDK_FORMAT_METHOD, 1, "%s", state))
+          .or(() -> flagViolation(tree, SLF4J_FORMAT_METHOD, 1, "{}", state))
+          .orElse(Description.NO_MATCH);
+    }
+
+    return Description.NO_MATCH;
+  }
+
+  /**
+   * Flags the given method invocation if it matches a targeted method and passes a non-compile time
+   * constant string concatenation as a format string.
+   */
+  private Optional<Description> flagViolation(
+      MethodInvocationTree tree,
+      Matcher<ExpressionTree> matcher,
+      int formatStringParam,
+      String formatSpecifier,
+      VisitorState state) {
+    if (!matcher.matches(tree, state)) {
+      /* The invoked method is not targeted by this check. */
+      return Optional.empty();
+    }
+
+    List<? extends ExpressionTree> arguments = tree.getArguments();
+
+    if (arguments.size() > formatStringParam + 1) {
+      /*
+       * This method invocation uses explicit string concatenation but _also_ already relies on
+       * format specifiers: flag but don't suggest a fix.
+       */
+      return Optional.of(describeMatch(tree));
+    }
+
+    ExpressionTree formatStringArg = arguments.get(formatStringParam);
+    ReplacementArgumentsConstructor replacementConstructor =
+        new ReplacementArgumentsConstructor(formatSpecifier);
+    formatStringArg.accept(replacementConstructor, state);
+
+    return Optional.of(
+        describeMatch(
+            tree,
+            SuggestedFix.replace(
+                formatStringArg, replacementConstructor.getReplacementArguments(state))));
+  }
+
+  private static boolean hasNonConstantStringConcatenationArgument(
+      MethodInvocationTree tree, int argPosition, VisitorState state) {
+    List<? extends ExpressionTree> arguments = tree.getArguments();
+    if (arguments.size() <= argPosition) {
+      /* This method doesn't accept enough parameters. */
+      return false;
+    }
+
+    ExpressionTree argument = ASTHelpers.stripParentheses(arguments.get(argPosition));
+    return argument instanceof BinaryTree
+        && isStringTyped(argument, state)
+        && ASTHelpers.constValue(argument, String.class) == null;
+  }
+
+  private static boolean isStringTyped(ExpressionTree tree, VisitorState state) {
+    return ASTHelpers.isSameType(ASTHelpers.getType(tree), state.getSymtab().stringType, state);
+  }
+
+  private static class ReplacementArgumentsConstructor
+      extends SimpleTreeVisitor<Void, VisitorState> {
+    private final StringBuilder formatString = new StringBuilder();
+    private final List<Tree> formatArguments = new ArrayList<>();
+    private final String formatSpecifier;
+
+    ReplacementArgumentsConstructor(String formatSpecifier) {
+      this.formatSpecifier = formatSpecifier;
+    }
+
+    @Nullable
+    @Override
+    public Void visitBinary(BinaryTree tree, VisitorState state) {
+      if (tree.getKind() == Kind.PLUS && isStringTyped(tree, state)) {
+        tree.getLeftOperand().accept(this, state);
+        tree.getRightOperand().accept(this, state);
+      } else {
+        appendExpression(tree);
+      }
+
+      return null;
+    }
+
+    @Nullable
+    @Override
+    public Void visitParenthesized(ParenthesizedTree tree, VisitorState state) {
+      return tree.getExpression().accept(this, state);
+    }
+
+    @Nullable
+    @Override
+    protected Void defaultAction(Tree tree, VisitorState state) {
+      appendExpression(tree);
+      return null;
+    }
+
+    private void appendExpression(Tree tree) {
+      if (tree instanceof LiteralTree) {
+        formatString.append(((LiteralTree) tree).getValue());
+      } else {
+        formatString.append(formatSpecifier);
+        formatArguments.add(tree);
+      }
+    }
+
+    private String getReplacementArguments(VisitorState state) {
+      return state.getConstantExpression(formatString.toString())
+          + ", "
+          + formatArguments.stream()
+              .map(tree -> SourceCode.treeToString(tree, state))
+              .collect(joining(", "));
+    }
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/IdentityConversion.java

@@ -0,0 +1,110 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.common.collect.ImmutableSet.toImmutableSet;
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+import static com.google.errorprone.matchers.Matchers.anyOf;
+import static com.google.errorprone.matchers.Matchers.staticMethod;
+import static com.google.errorprone.suppliers.Suppliers.OBJECT_TYPE;
+
+import com.google.auto.service.AutoService;
+import com.google.common.primitives.Primitives;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
+import com.google.errorprone.bugpatterns.TypesWithUndefinedEquality;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.fixes.SuggestedFixes;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.google.errorprone.util.ASTHelpers;
+import com.google.errorprone.util.ASTHelpers.TargetType;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.MethodInvocationTree;
+import com.sun.tools.javac.code.Type;
+import com.sun.tools.javac.code.Types;
+import java.util.Arrays;
+import java.util.List;
+import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+
+/** A {@link BugChecker} that flags redundant identity conversions. */
+// XXX: Consider detecting cases where a flagged expression is passed to a method, and where removal
+// of the identify conversion would cause a different method overload to be selected. Depending on
+// the target method such a modification may change the code's semantics or performance.
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "Avoid or clarify identity conversions",
+    linkType = NONE,
+    severity = WARNING,
+    tags = SIMPLIFICATION)
+public final class IdentityConversion extends BugChecker implements MethodInvocationTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Matcher<ExpressionTree> IS_CONVERSION_METHOD =
+      anyOf(
+          staticMethod()
+              .onClassAny(
+                  "com.google.common.collect.ImmutableBiMap",
+                  "com.google.common.collect.ImmutableList",
+                  "com.google.common.collect.ImmutableListMultimap",
+                  "com.google.common.collect.ImmutableMap",
+                  "com.google.common.collect.ImmutableMultimap",
+                  "com.google.common.collect.ImmutableMultiset",
+                  "com.google.common.collect.ImmutableRangeMap",
+                  "com.google.common.collect.ImmutableRangeSet",
+                  "com.google.common.collect.ImmutableSet",
+                  "com.google.common.collect.ImmutableSetMultimap",
+                  "com.google.common.collect.ImmutableTable")
+              .named("copyOf"),
+          staticMethod()
+              .onClassAny(
+                  Primitives.allWrapperTypes().stream()
+                      .map(Class::getName)
+                      .collect(toImmutableSet()))
+              .named("valueOf"),
+          staticMethod().onClass(String.class.getName()).named("valueOf"),
+          staticMethod().onClass("reactor.adapter.rxjava.RxJava2Adapter"),
+          staticMethod()
+              .onClass("reactor.core.publisher.Flux")
+              .namedAnyOf("concat", "firstWithSignal", "from", "merge"),
+          staticMethod().onClass("reactor.core.publisher.Mono").namedAnyOf("from", "fromDirect"));
+
+  @Override
+  public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    List<? extends ExpressionTree> arguments = tree.getArguments();
+    if (arguments.size() != 1 || !IS_CONVERSION_METHOD.matches(tree, state)) {
+      return Description.NO_MATCH;
+    }
+
+    ExpressionTree sourceTree = arguments.get(0);
+    Type sourceType = ASTHelpers.getType(sourceTree);
+    Type resultType = ASTHelpers.getType(tree);
+    TargetType targetType = ASTHelpers.targetType(state);
+    if (sourceType == null || resultType == null || targetType == null) {
+      return Description.NO_MATCH;
+    }
+
+    if (!state.getTypes().isSameType(sourceType, resultType)
+        && !isConvertibleWithWellDefinedEquality(sourceType, targetType.type(), state)) {
+      return Description.NO_MATCH;
+    }
+
+    return buildDescription(tree)
+        .setMessage(
+            "This method invocation appears redundant; remove it or suppress this warning and "
+                + "add a comment explaining its purpose")
+        .addFix(SuggestedFix.replace(tree, SourceCode.treeToString(sourceTree, state)))
+        .addFix(SuggestedFixes.addSuppressWarnings(state, canonicalName()))
+        .build();
+  }
+
+  private static boolean isConvertibleWithWellDefinedEquality(
+      Type sourceType, Type targetType, VisitorState state) {
+    Types types = state.getTypes();
+    return !types.isSameType(targetType, OBJECT_TYPE.get(state))
+        && types.isConvertible(sourceType, targetType)
+        && Arrays.stream(TypesWithUndefinedEquality.values())
+            .noneMatch(b -> b.matchesType(sourceType, state) || b.matchesType(targetType, state));
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/ImmutablesSortedSetComparator.java

@@ -0,0 +1,81 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.ERROR;
+import static com.google.errorprone.BugPattern.StandardTags.LIKELY_ERROR;
+import static com.google.errorprone.matchers.Matchers.allOf;
+import static com.google.errorprone.matchers.Matchers.anyOf;
+import static com.google.errorprone.matchers.Matchers.enclosingClass;
+import static com.google.errorprone.matchers.Matchers.hasAnnotation;
+import static com.google.errorprone.matchers.Matchers.hasModifier;
+import static com.google.errorprone.matchers.Matchers.isSubtypeOf;
+import static com.google.errorprone.matchers.Matchers.methodReturns;
+import static com.google.errorprone.matchers.Matchers.not;
+
+import com.google.auto.service.AutoService;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.fixes.SuggestedFixes;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.sun.source.tree.MethodTree;
+import java.util.SortedSet;
+import javax.lang.model.element.Modifier;
+
+/**
+ * A {@link BugChecker} which flags {@link SortedSet} property declarations inside
+ * {@code @Value.Immutable}- and {@code @Value.Modifiable}-annotated types that lack a
+ * {@code @Value.NaturalOrder} or {@code @Value.ReverseOrder} annotation.
+ *
+ * <p>Without such an annotation:
+ *
+ * <ul>
+ *   <li>deserialization of the enclosing type requires that the associated JSON property is
+ *       present, contrary to the way in which Immutables handles other collection properties; and
+ *   <li>different instances may use different comparator implementations (e.g. deserialization
+ *       would default to natural order sorting), potentially leading to subtle bugs.
+ * </ul>
+ */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary =
+        "`SortedSet` properties of a `@Value.Immutable` or `@Value.Modifiable` type must be "
+            + "annotated with `@Value.NaturalOrder` or `@Value.ReverseOrder`",
+    linkType = NONE,
+    severity = ERROR,
+    tags = LIKELY_ERROR)
+public final class ImmutablesSortedSetComparator extends BugChecker implements MethodTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Matcher<MethodTree> METHOD_LACKS_ANNOTATION =
+      allOf(
+          methodReturns(isSubtypeOf(SortedSet.class)),
+          anyOf(
+              allOf(
+                  hasModifier(Modifier.ABSTRACT),
+                  enclosingClass(
+                      anyOf(
+                          hasAnnotation("org.immutables.value.Value.Immutable"),
+                          hasAnnotation("org.immutables.value.Value.Modifiable")))),
+              hasAnnotation("org.immutables.value.Value.Default")),
+          not(
+              anyOf(
+                  hasAnnotation("org.immutables.value.Value.NaturalOrder"),
+                  hasAnnotation("org.immutables.value.Value.ReverseOrder"))));
+
+  @Override
+  public Description matchMethod(MethodTree tree, VisitorState state) {
+    if (!METHOD_LACKS_ANNOTATION.matches(tree, state)) {
+      return Description.NO_MATCH;
+    }
+
+    SuggestedFix.Builder builder = SuggestedFix.builder();
+    String valueTypeIdentifier =
+        SuggestedFixes.qualifyType(state, builder, "org.immutables.value.Value");
+    return describeMatch(
+        tree,
+        builder.prefixWith(tree, String.format("@%s.NaturalOrder ", valueTypeIdentifier)).build());
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/JUnitMethodDeclaration.java

@@ -0,0 +1,200 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+import static com.google.errorprone.matchers.ChildMultiMatcher.MatchType.AT_LEAST_ONE;
+import static com.google.errorprone.matchers.Matchers.allOf;
+import static com.google.errorprone.matchers.Matchers.annotations;
+import static com.google.errorprone.matchers.Matchers.anyOf;
+import static com.google.errorprone.matchers.Matchers.enclosingClass;
+import static com.google.errorprone.matchers.Matchers.hasModifier;
+import static com.google.errorprone.matchers.Matchers.isType;
+import static java.util.function.Predicate.not;
+import static tech.picnic.errorprone.bugpatterns.util.JavaKeywords.isReservedKeyword;
+
+import com.google.auto.service.AutoService;
+import com.google.common.collect.ImmutableSet;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.fixes.SuggestedFixes;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.google.errorprone.matchers.Matchers;
+import com.google.errorprone.matchers.MultiMatcher;
+import com.google.errorprone.predicates.TypePredicate;
+import com.google.errorprone.util.ASTHelpers;
+import com.sun.source.tree.AnnotationTree;
+import com.sun.source.tree.ClassTree;
+import com.sun.source.tree.ImportTree;
+import com.sun.source.tree.MethodTree;
+import com.sun.source.tree.Tree;
+import com.sun.tools.javac.code.Symbol;
+import java.util.Optional;
+import javax.lang.model.element.Modifier;
+import javax.lang.model.element.Name;
+import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+
+/** A {@link BugChecker} which flags non-canonical JUnit method declarations. */
+// XXX: Consider introducing a class-level check which enforces that test classes:
+// 1. Are named `*Test` or `Abstract*TestCase`.
+// 2. If not `abstract`, are package-private and don't have public methods and subclasses.
+// 3. Only have private fields.
+// XXX: If implemented, the current logic could flag only `private` JUnit methods.
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "JUnit method declaration can likely be improved",
+    linkType = NONE,
+    severity = SUGGESTION,
+    tags = SIMPLIFICATION)
+public final class JUnitMethodDeclaration extends BugChecker implements MethodTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final String TEST_PREFIX = "test";
+  private static final ImmutableSet<Modifier> ILLEGAL_MODIFIERS =
+      ImmutableSet.of(Modifier.PRIVATE, Modifier.PROTECTED, Modifier.PUBLIC);
+  private static final Matcher<MethodTree> HAS_UNMODIFIABLE_SIGNATURE =
+      anyOf(
+          annotations(AT_LEAST_ONE, isType("java.lang.Override")),
+          allOf(
+              Matchers.not(hasModifier(Modifier.FINAL)),
+              Matchers.not(hasModifier(Modifier.PRIVATE)),
+              enclosingClass(hasModifier(Modifier.ABSTRACT))));
+  private static final MultiMatcher<MethodTree, AnnotationTree> TEST_METHOD =
+      annotations(
+          AT_LEAST_ONE,
+          anyOf(
+              isType("org.junit.jupiter.api.Test"),
+              hasMetaAnnotation("org.junit.jupiter.api.TestTemplate")));
+  private static final MultiMatcher<MethodTree, AnnotationTree> SETUP_OR_TEARDOWN_METHOD =
+      annotations(
+          AT_LEAST_ONE,
+          anyOf(
+              isType("org.junit.jupiter.api.AfterAll"),
+              isType("org.junit.jupiter.api.AfterEach"),
+              isType("org.junit.jupiter.api.BeforeAll"),
+              isType("org.junit.jupiter.api.BeforeEach")));
+
+  @Override
+  public Description matchMethod(MethodTree tree, VisitorState state) {
+    if (HAS_UNMODIFIABLE_SIGNATURE.matches(tree, state)) {
+      return Description.NO_MATCH;
+    }
+
+    boolean isTestMethod = TEST_METHOD.matches(tree, state);
+    if (!isTestMethod && !SETUP_OR_TEARDOWN_METHOD.matches(tree, state)) {
+      return Description.NO_MATCH;
+    }
+
+    SuggestedFix.Builder fixBuilder = SuggestedFix.builder();
+    SuggestedFixes.removeModifiers(tree.getModifiers(), state, ILLEGAL_MODIFIERS)
+        .ifPresent(fixBuilder::merge);
+
+    if (isTestMethod) {
+      suggestTestMethodRenameIfApplicable(tree, fixBuilder, state);
+    }
+
+    return fixBuilder.isEmpty() ? Description.NO_MATCH : describeMatch(tree, fixBuilder.build());
+  }
+
+  private void suggestTestMethodRenameIfApplicable(
+      MethodTree tree, SuggestedFix.Builder fixBuilder, VisitorState state) {
+    tryCanonicalizeMethodName(tree)
+        .ifPresent(
+            newName ->
+                findMethodRenameBlocker(newName, state)
+                    .ifPresentOrElse(
+                        blocker -> reportMethodRenameBlocker(tree, blocker, state),
+                        () -> fixBuilder.merge(SuggestedFixes.renameMethod(tree, newName, state))));
+  }
+
+  private void reportMethodRenameBlocker(MethodTree tree, String reason, VisitorState state) {
+    state.reportMatch(
+        buildDescription(tree)
+            .setMessage(
+                String.format(
+                    "This method's name should not redundantly start with `%s` (but note that %s)",
+                    TEST_PREFIX, reason))
+            .build());
+  }
+
+  /**
+   * If applicable, returns a human-readable argument against assigning the given name to an
+   * existing method.
+   *
+   * <p>This method implements imperfect heuristics. Things it currently does not consider include
+   * the following:
+   *
+   * <ul>
+   *   <li>Whether the rename would merely introduce a method overload, rather than clashing with an
+   *       existing method declaration.
+   *   <li>Whether the rename would cause a method in a superclass to be overridden.
+   *   <li>Whether the rename would in fact clash with a static import. (It could be that a static
+   *       import of the same name is only referenced from lexical scopes in which the method under
+   *       consideration cannot be referenced directly.)
+   * </ul>
+   */
+  private static Optional<String> findMethodRenameBlocker(String methodName, VisitorState state) {
+    if (isMethodInEnclosingClass(methodName, state)) {
+      return Optional.of(
+          String.format("a method named `%s` already exists in this class", methodName));
+    }
+
+    if (isSimpleNameStaticallyImported(methodName, state)) {
+      return Optional.of(String.format("`%s` is already statically imported", methodName));
+    }
+
+    if (isReservedKeyword(methodName)) {
+      return Optional.of(String.format("`%s` is a reserved keyword", methodName));
+    }
+
+    return Optional.empty();
+  }
+
+  private static boolean isMethodInEnclosingClass(String methodName, VisitorState state) {
+    return state.findEnclosing(ClassTree.class).getMembers().stream()
+        .filter(MethodTree.class::isInstance)
+        .map(MethodTree.class::cast)
+        .map(MethodTree::getName)
+        .map(Name::toString)
+        .anyMatch(methodName::equals);
+  }
+
+  private static boolean isSimpleNameStaticallyImported(String simpleName, VisitorState state) {
+    return state.getPath().getCompilationUnit().getImports().stream()
+        .filter(ImportTree::isStatic)
+        .map(ImportTree::getQualifiedIdentifier)
+        .map(tree -> getStaticImportSimpleName(tree, state))
+        .anyMatch(simpleName::contentEquals);
+  }
+
+  private static CharSequence getStaticImportSimpleName(Tree tree, VisitorState state) {
+    String source = SourceCode.treeToString(tree, state);
+    return source.subSequence(source.lastIndexOf('.') + 1, source.length());
+  }
+
+  private static Optional<String> tryCanonicalizeMethodName(MethodTree tree) {
+    return Optional.of(ASTHelpers.getSymbol(tree).getQualifiedName().toString())
+        .filter(name -> name.startsWith(TEST_PREFIX))
+        .map(name -> name.substring(TEST_PREFIX.length()))
+        .filter(not(String::isEmpty))
+        .map(name -> Character.toLowerCase(name.charAt(0)) + name.substring(1))
+        .filter(name -> !Character.isDigit(name.charAt(0)));
+  }
+
+  // XXX: Move to a `MoreMatchers` utility class.
+  private static Matcher<AnnotationTree> hasMetaAnnotation(String annotationClassName) {
+    TypePredicate typePredicate = hasAnnotation(annotationClassName);
+    return (tree, state) -> {
+      Symbol sym = ASTHelpers.getSymbol(tree);
+      return sym != null && typePredicate.apply(sym.type, state);
+    };
+  }
+
+  // XXX: Move to a `MoreTypePredicates` utility class.
+  private static TypePredicate hasAnnotation(String annotationClassName) {
+    return (type, state) -> ASTHelpers.hasAnnotation(type.tsym, annotationClassName, state);
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/LexicographicalAnnotationAttributeListing.java

@@ -1,5 +1,10 @@
 package tech.picnic.errorprone.bugpatterns;
 
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static com.google.errorprone.BugPattern.StandardTags.STYLE;
+import static java.util.Comparator.comparing;
+import static java.util.Comparator.naturalOrder;
 import static java.util.stream.Collectors.joining;
 
 import com.google.auto.service.AutoService;
@@ -7,10 +12,6 @@ import com.google.common.collect.Comparators;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.errorprone.BugPattern;
-import com.google.errorprone.BugPattern.LinkType;
-import com.google.errorprone.BugPattern.ProvidesFix;
-import com.google.errorprone.BugPattern.SeverityLevel;
-import com.google.errorprone.BugPattern.StandardTags;
 import com.google.errorprone.ErrorProneFlags;
 import com.google.errorprone.VisitorState;
 import com.google.errorprone.bugpatterns.BugChecker;
@@ -31,12 +32,14 @@ import com.sun.source.tree.Tree.Kind;
 import com.sun.source.util.TreeScanner;
 import com.sun.tools.javac.code.Symtab;
 import com.sun.tools.javac.code.Type;
-import java.util.Comparator;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Optional;
 import java.util.Set;
 import java.util.stream.Stream;
+import javax.annotation.Nullable;
+import tech.picnic.errorprone.bugpatterns.util.AnnotationAttributeMatcher;
+import tech.picnic.errorprone.bugpatterns.util.SourceCode;
 
 /**
  * A {@link BugChecker} which flags annotation array listings which aren't sorted lexicographically.
@@ -46,13 +49,11 @@ import java.util.stream.Stream;
  */
 @AutoService(BugChecker.class)
 @BugPattern(
-    name = "LexicographicalAnnotationAttributeListing",
     summary = "Where possible, sort annotation array attributes lexicographically",
-    linkType = LinkType.NONE,
-    severity = SeverityLevel.SUGGESTION,
-    tags = StandardTags.STYLE,
-    providesFix = ProvidesFix.REQUIRES_HUMAN_ATTENTION)
-public final class LexicographicalAnnotationAttributeListingCheck extends BugChecker
+    linkType = NONE,
+    severity = SUGGESTION,
+    tags = STYLE)
+public final class LexicographicalAnnotationAttributeListing extends BugChecker
     implements AnnotationTreeMatcher {
   private static final long serialVersionUID = 1L;
   private static final ImmutableSet<String> BLACKLISTED_ANNOTATIONS =
@@ -60,24 +61,28 @@ public final class LexicographicalAnnotationAttributeListingCheck extends BugChe
           // XXX: unless JsonPropertyOrder#alphabetic is true...
           "com.fasterxml.jackson.annotation.JsonPropertyOrder#value",
           "io.swagger.annotations.ApiImplicitParams#value",
-          "javax.xml.bind.annotation.XmlType#propOrder");
+          "io.swagger.v3.oas.annotations.Parameters#value",
+          "javax.xml.bind.annotation.XmlType#propOrder",
+          "org.springframework.context.annotation.PropertySource#value",
+          "org.springframework.test.context.TestPropertySource#locations",
+          "org.springframework.test.context.TestPropertySource#value");
   private static final String FLAG_PREFIX = "LexicographicalAnnotationAttributeListing:";
   private static final String INCLUDED_ANNOTATIONS_FLAG = FLAG_PREFIX + "Includes";
   private static final String EXCLUDED_ANNOTATIONS_FLAG = FLAG_PREFIX + "Excludes";
 
   private final AnnotationAttributeMatcher matcher;
 
-  /** Instantiates the default {@link LexicographicalAnnotationAttributeListingCheck}. */
-  public LexicographicalAnnotationAttributeListingCheck() {
+  /** Instantiates the default {@link LexicographicalAnnotationAttributeListing}. */
+  public LexicographicalAnnotationAttributeListing() {
     this(ErrorProneFlags.empty());
   }
 
   /**
-   * Instantiates a customized {@link LexicographicalAnnotationAttributeListingCheck}.
+   * Instantiates a customized {@link LexicographicalAnnotationAttributeListing}.
    *
    * @param flags Any provided command line flags.
    */
-  public LexicographicalAnnotationAttributeListingCheck(ErrorProneFlags flags) {
+  public LexicographicalAnnotationAttributeListing(ErrorProneFlags flags) {
     matcher = createAnnotationAttributeMatcher(flags);
   }
 
@@ -128,7 +133,7 @@ public final class LexicographicalAnnotationAttributeListingCheck extends BugChe
     /* The elements aren't sorted. Suggest the sorted alternative. */
     String suggestion =
         desiredOrdering.stream()
-            .map(expr -> Util.treeToString(expr, state))
+            .map(expr -> SourceCode.treeToString(expr, state))
             .collect(joining(", ", "{", "}"));
     return Optional.of(SuggestedFix.builder().replace(array, suggestion));
   }
@@ -150,11 +155,14 @@ public final class LexicographicalAnnotationAttributeListingCheck extends BugChe
 
   private static ImmutableList<? extends ExpressionTree> doSort(
       Iterable<? extends ExpressionTree> elements, VisitorState state) {
+    // XXX: Perhaps we should use `Collator` with `.setStrength(Collator.PRIMARY)` and
+    // `getCollationKey`. Not clear whether that's worth the hassle at this point.
     return ImmutableList.sortedCopyOf(
-        Comparator.comparing(
+        comparing(
             e -> getStructure(e, state),
             Comparators.lexicographical(
-                Comparators.lexicographical(Comparator.<String>naturalOrder()))),
+                Comparators.lexicographical(
+                    String.CASE_INSENSITIVE_ORDER.thenComparing(naturalOrder())))),
         elements);
   }
 
@@ -168,20 +176,23 @@ public final class LexicographicalAnnotationAttributeListingCheck extends BugChe
     ImmutableList.Builder<ImmutableList<String>> nodes = ImmutableList.builder();
 
     new TreeScanner<Void, Void>() {
+      @Nullable
       @Override
-      public Void visitIdentifier(IdentifierTree node, Void ctx) {
+      public Void visitIdentifier(IdentifierTree node, @Nullable Void ctx) {
         nodes.add(tokenize(node));
         return super.visitIdentifier(node, ctx);
       }
 
+      @Nullable
       @Override
-      public Void visitLiteral(LiteralTree node, Void ctx) {
+      public Void visitLiteral(LiteralTree node, @Nullable Void ctx) {
         nodes.add(tokenize(node));
         return super.visitLiteral(node, ctx);
       }
 
+      @Nullable
       @Override
-      public Void visitPrimitiveType(PrimitiveTypeTree node, Void ctx) {
+      public Void visitPrimitiveType(PrimitiveTypeTree node, @Nullable Void ctx) {
         nodes.add(tokenize(node));
         return super.visitPrimitiveType(node, ctx);
       }
@@ -191,7 +202,7 @@ public final class LexicographicalAnnotationAttributeListingCheck extends BugChe
          * Tokens are split on `=` so that e.g. inline Spring property declarations are properly
          * sorted by key, then value.
          */
-        return ImmutableList.copyOf(Util.treeToString(node, state).split("=", -1));
+        return ImmutableList.copyOf(SourceCode.treeToString(node, state).split("=", -1));
       }
     }.scan(array, null);
 

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/LexicographicalAnnotationListing.java

@@ -0,0 +1,80 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.common.collect.ImmutableList.toImmutableList;
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static com.google.errorprone.BugPattern.StandardTags.STYLE;
+import static java.util.Comparator.comparing;
+
+import com.google.auto.service.AutoService;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Streams;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodTreeMatcher;
+import com.google.errorprone.fixes.Fix;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.matchers.Description;
+import com.sun.source.tree.AnnotationTree;
+import com.sun.source.tree.MethodTree;
+import java.util.List;
+import java.util.Optional;
+import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+
+/**
+ * A {@link BugChecker} that flags annotations that are not lexicographically sorted.
+ *
+ * <p>The idea behind this checker is that maintaining a sorted sequence simplifies conflict
+ * resolution, and can even avoid it if two branches add the same annotation.
+ */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "Sort annotations lexicographically where possible",
+    linkType = NONE,
+    severity = SUGGESTION,
+    tags = STYLE)
+public final class LexicographicalAnnotationListing extends BugChecker
+    implements MethodTreeMatcher {
+  private static final long serialVersionUID = 1L;
+
+  @Override
+  public Description matchMethod(MethodTree tree, VisitorState state) {
+    List<? extends AnnotationTree> originalOrdering = tree.getModifiers().getAnnotations();
+    if (originalOrdering.size() < 2) {
+      return Description.NO_MATCH;
+    }
+
+    ImmutableList<? extends AnnotationTree> sortedAnnotations = sort(originalOrdering, state);
+    if (originalOrdering.equals(sortedAnnotations)) {
+      return Description.NO_MATCH;
+    }
+
+    Optional<Fix> fix = tryFixOrdering(originalOrdering, sortedAnnotations, state);
+
+    Description.Builder description = buildDescription(originalOrdering.get(0));
+    fix.ifPresent(description::addFix);
+    return description.build();
+  }
+
+  private static ImmutableList<? extends AnnotationTree> sort(
+      List<? extends AnnotationTree> annotations, VisitorState state) {
+    return annotations.stream()
+        .sorted(comparing(annotation -> SourceCode.treeToString(annotation, state)))
+        .collect(toImmutableList());
+  }
+
+  private static Optional<Fix> tryFixOrdering(
+      List<? extends AnnotationTree> originalAnnotations,
+      ImmutableList<? extends AnnotationTree> sortedAnnotations,
+      VisitorState state) {
+    return Streams.zip(
+            originalAnnotations.stream(),
+            sortedAnnotations.stream(),
+            (original, replacement) ->
+                SuggestedFix.builder()
+                    .replace(original, SourceCode.treeToString(replacement, state)))
+        .reduce(SuggestedFix.Builder::merge)
+        .map(SuggestedFix.Builder::build);
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/MethodReferenceUsage.java

@@ -1,15 +1,14 @@
 package tech.picnic.errorprone.bugpatterns;
 
 import static com.google.common.collect.ImmutableList.toImmutableList;
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static com.google.errorprone.BugPattern.StandardTags.STYLE;
 
 import com.google.auto.service.AutoService;
 import com.google.common.base.VerifyException;
 import com.google.common.collect.ImmutableList;
 import com.google.errorprone.BugPattern;
-import com.google.errorprone.BugPattern.LinkType;
-import com.google.errorprone.BugPattern.ProvidesFix;
-import com.google.errorprone.BugPattern.SeverityLevel;
-import com.google.errorprone.BugPattern.StandardTags;
 import com.google.errorprone.VisitorState;
 import com.google.errorprone.bugpatterns.BugChecker;
 import com.google.errorprone.bugpatterns.BugChecker.LambdaExpressionTreeMatcher;
@@ -48,16 +47,15 @@ import javax.lang.model.element.Name;
 // black-and-white. Maybe we can more closely approximate it?
 // XXX: With Java 9's introduction of `Predicate.not`, we could write many lambda expressions to
 // `not(some::reference)`.
+// XXX: This check is extremely inefficient due to its reliance on `SuggestedFixes.compilesWithFix`.
+// Palantir's `LambdaMethodReference` check seems to suffer a similar issue at this time.
 @AutoService(BugChecker.class)
 @BugPattern(
-    name = "MethodReferenceUsage",
     summary = "Prefer method references over lambda expressions",
-    linkType = LinkType.NONE,
-    severity = SeverityLevel.SUGGESTION,
-    tags = StandardTags.STYLE,
-    providesFix = ProvidesFix.REQUIRES_HUMAN_ATTENTION)
-public final class MethodReferenceUsageCheck extends BugChecker
-    implements LambdaExpressionTreeMatcher {
+    linkType = NONE,
+    severity = SUGGESTION,
+    tags = STYLE)
+public final class MethodReferenceUsage extends BugChecker implements LambdaExpressionTreeMatcher {
   private static final long serialVersionUID = 1L;
 
   @Override
@@ -69,7 +67,10 @@ public final class MethodReferenceUsageCheck extends BugChecker
      */
     return constructMethodRef(tree, tree.getBody())
         .map(SuggestedFix.Builder::build)
-        .filter(fix -> SuggestedFixes.compilesWithFix(fix, state))
+        .filter(
+            fix ->
+                SuggestedFixes.compilesWithFix(
+                    fix, state, ImmutableList.of(), /* onlyInSameCompilationUnit= */ true))
         .map(fix -> describeMatch(tree, fix))
         .orElse(Description.NO_MATCH);
   }
@@ -99,6 +100,8 @@ public final class MethodReferenceUsageCheck extends BugChecker
         .flatMap(statements -> constructMethodRef(lambdaExpr, statements.get(0)));
   }
 
+  // XXX: Replace nested `Optional` usage.
+  @SuppressWarnings("NestedOptionals")
   private static Optional<SuggestedFix.Builder> constructMethodRef(
       LambdaExpressionTree lambdaExpr, MethodInvocationTree subTree) {
     return matchArguments(lambdaExpr, subTree)
@@ -155,6 +158,8 @@ public final class MethodReferenceUsageCheck extends BugChecker
     return constructFix(lambdaExpr, lhsType.tsym, subTree.getIdentifier());
   }
 
+  // XXX: Refactor or replace inner `Optional` with a custom type.
+  @SuppressWarnings("NestedOptionals")
   private static Optional<Optional<Name>> matchArguments(
       LambdaExpressionTree lambdaExpr, MethodInvocationTree subTree) {
     ImmutableList<Name> expectedArguments = getVariables(lambdaExpr);

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/MissingRefasterAnnotation.java

@@ -0,0 +1,54 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
+import static com.google.errorprone.BugPattern.StandardTags.LIKELY_ERROR;
+import static com.google.errorprone.matchers.ChildMultiMatcher.MatchType.AT_LEAST_ONE;
+import static com.google.errorprone.matchers.Matchers.annotations;
+import static com.google.errorprone.matchers.Matchers.anyOf;
+import static com.google.errorprone.matchers.Matchers.isType;
+
+import com.google.auto.service.AutoService;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.ClassTreeMatcher;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.MultiMatcher;
+import com.google.errorprone.util.ASTHelpers;
+import com.sun.source.tree.AnnotationTree;
+import com.sun.source.tree.ClassTree;
+import com.sun.source.tree.MethodTree;
+import com.sun.source.tree.Tree;
+
+/** A {@link BugChecker} that flags likely missing Refaster annotations. */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "The Refaster template contains a method without any Refaster annotations",
+    linkType = NONE,
+    severity = WARNING,
+    tags = LIKELY_ERROR)
+public final class MissingRefasterAnnotation extends BugChecker implements ClassTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final MultiMatcher<Tree, AnnotationTree> REFASTER_ANNOTATION =
+      annotations(
+          AT_LEAST_ONE,
+          anyOf(
+              isType("com.google.errorprone.refaster.annotation.Placeholder"),
+              isType("com.google.errorprone.refaster.annotation.BeforeTemplate"),
+              isType("com.google.errorprone.refaster.annotation.AfterTemplate")));
+
+  @Override
+  public Description matchClass(ClassTree tree, VisitorState state) {
+    long methodTypes =
+        tree.getMembers().stream()
+            .filter(member -> member.getKind() == Tree.Kind.METHOD)
+            .map(MethodTree.class::cast)
+            .filter(method -> !ASTHelpers.isGeneratedConstructor(method))
+            .map(method -> REFASTER_ANNOTATION.matches(method, state))
+            .distinct()
+            .count();
+
+    return methodTypes < 2 ? Description.NO_MATCH : buildDescription(tree).build();
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/MockitoStubbing.java

@@ -0,0 +1,58 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+import static com.google.errorprone.matchers.Matchers.staticMethod;
+
+import com.google.auto.service.AutoService;
+import com.google.common.collect.Iterables;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.MethodInvocationTree;
+import java.util.List;
+import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+
+/**
+ * A {@link BugChecker} which flags method invocations for which all arguments are wrapped using
+ * {@link org.mockito.Mockito#eq}; this is redundant.
+ */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "Don't unnecessarily use Mockito's `eq(...)`",
+    linkType = NONE,
+    severity = SUGGESTION,
+    tags = SIMPLIFICATION)
+public final class MockitoStubbing extends BugChecker implements MethodInvocationTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Matcher<ExpressionTree> MOCKITO_EQ_METHOD =
+      staticMethod().onClass("org.mockito.ArgumentMatchers").named("eq");
+
+  @Override
+  public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    List<? extends ExpressionTree> arguments = tree.getArguments();
+    if (arguments.isEmpty() || !arguments.stream().allMatch(arg -> isEqInvocation(arg, state))) {
+      return Description.NO_MATCH;
+    }
+
+    SuggestedFix.Builder suggestedFix = SuggestedFix.builder();
+    for (ExpressionTree arg : arguments) {
+      suggestedFix.replace(
+          arg,
+          SourceCode.treeToString(
+              Iterables.getOnlyElement(((MethodInvocationTree) arg).getArguments()), state));
+    }
+
+    return describeMatch(tree, suggestedFix.build());
+  }
+
+  private static boolean isEqInvocation(ExpressionTree tree, VisitorState state) {
+    return tree instanceof MethodInvocationTree && MOCKITO_EQ_METHOD.matches(tree, state);
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/NestedOptionals.java

@@ -0,0 +1,51 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
+import static com.google.errorprone.BugPattern.StandardTags.FRAGILE_CODE;
+
+import com.google.auto.service.AutoService;
+import com.google.common.collect.Iterables;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.suppliers.Supplier;
+import com.google.errorprone.suppliers.Suppliers;
+import com.google.errorprone.util.ASTHelpers;
+import com.sun.source.tree.MethodInvocationTree;
+import com.sun.source.tree.Tree;
+import com.sun.tools.javac.code.Type;
+import com.sun.tools.javac.util.List;
+import java.util.Optional;
+
+/** A {@link BugChecker} which flags nesting of {@link Optional Optionals}. */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary =
+        "Avoid nesting `Optional`s inside `Optional`s; the resultant code is hard to reason about",
+    linkType = NONE,
+    severity = WARNING,
+    tags = FRAGILE_CODE)
+public final class NestedOptionals extends BugChecker implements MethodInvocationTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Supplier<Type> OPTIONAL = Suppliers.typeFromClass(Optional.class);
+
+  @Override
+  public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    return isOptionalOfOptional(tree, state) ? describeMatch(tree) : Description.NO_MATCH;
+  }
+
+  private static boolean isOptionalOfOptional(Tree tree, VisitorState state) {
+    Type optionalType = OPTIONAL.get(state);
+    Type type = ASTHelpers.getType(tree);
+    if (!ASTHelpers.isSubtype(type, optionalType, state)) {
+      return false;
+    }
+
+    List<Type> typeArguments = type.getTypeArguments();
+    return !typeArguments.isEmpty()
+        && ASTHelpers.isSubtype(Iterables.getOnlyElement(typeArguments), optionalType, state);
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/NonEmptyMono.java

@@ -0,0 +1,91 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+import static com.google.errorprone.matchers.Matchers.anyOf;
+import static com.google.errorprone.matchers.Matchers.instanceMethod;
+
+import com.google.auto.service.AutoService;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.google.errorprone.util.ASTHelpers;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.MethodInvocationTree;
+import java.util.function.BiFunction;
+import reactor.core.publisher.Mono;
+import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+
+/**
+ * A {@link BugChecker} which flags {@link Mono} operations that are known to be vacuous, given that
+ * they are invoked on a {@link Mono} that is known not to complete empty.
+ */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "Avoid vacuous operations on known non-empty `Mono`s",
+    linkType = NONE,
+    severity = WARNING,
+    tags = SIMPLIFICATION)
+// XXX: This check does not simplify `someFlux.defaultIfEmpty(T).{defaultIfEmpty(T),hasElements()}`,
+// as `someFlux.defaultIfEmpty(T)` yields a `Flux` rather than a `Mono`. Consider adding support for
+// these cases.
+// XXX: Given more advanced analysis many more expressions could be flagged. Consider
+// `Mono.just(someValue)`, `Flux.just(someNonEmptySequence)`,
+// `someMono.switchIfEmpty(someProvablyNonEmptyMono)` and many other variants.
+// XXX: Consider implementing a similar check for `Publisher`s that are known to complete without
+// emitting a value (e.g. `Mono.empty()`, `someFlux.then()`, ...), or known not to complete normally
+// (`Mono.never()`, `someFlux.repeat()`, `Mono.error(...)`, ...). The latter category could
+// potentially be split out further.
+public final class NonEmptyMono extends BugChecker implements MethodInvocationTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Matcher<ExpressionTree> MONO_SIZE_CHECK =
+      instanceMethod()
+          .onDescendantOf("reactor.core.publisher.Mono")
+          .namedAnyOf("defaultIfEmpty", "single", "switchIfEmpty");
+  private static final Matcher<ExpressionTree> NON_EMPTY_MONO =
+      anyOf(
+          instanceMethod()
+              .onDescendantOf("reactor.core.publisher.Flux")
+              .namedAnyOf(
+                  "all",
+                  "any",
+                  "collect",
+                  "collectList",
+                  "collectMap",
+                  "collectMultimap",
+                  "collectSortedList",
+                  "count",
+                  "elementAt",
+                  "hasElement",
+                  "hasElements",
+                  "last",
+                  "reduceWith",
+                  "single"),
+          instanceMethod()
+              .onDescendantOf("reactor.core.publisher.Flux")
+              .named("reduce")
+              .withParameters(Object.class.getName(), BiFunction.class.getName()),
+          instanceMethod()
+              .onDescendantOf("reactor.core.publisher.Mono")
+              .namedAnyOf("defaultIfEmpty", "hasElement", "single"));
+
+  @Override
+  public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    if (!MONO_SIZE_CHECK.matches(tree, state)) {
+      return Description.NO_MATCH;
+    }
+
+    ExpressionTree receiver = ASTHelpers.getReceiver(tree);
+    if (!NON_EMPTY_MONO.matches(receiver, state)) {
+      return Description.NO_MATCH;
+    }
+
+    return describeMatch(
+        tree, SuggestedFix.replace(tree, SourceCode.treeToString(receiver, state)));
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/PrimitiveComparison.java

@@ -1,16 +1,16 @@
 package tech.picnic.errorprone.bugpatterns;
 
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
+import static com.google.errorprone.BugPattern.StandardTags.PERFORMANCE;
+import static com.google.errorprone.matchers.Matchers.anyOf;
 import static com.google.errorprone.matchers.method.MethodMatchers.instanceMethod;
 import static com.google.errorprone.matchers.method.MethodMatchers.staticMethod;
-import static java.util.function.Predicate.not;
+import static java.util.stream.Collectors.joining;
 
 import com.google.auto.service.AutoService;
 import com.google.common.base.VerifyException;
 import com.google.errorprone.BugPattern;
-import com.google.errorprone.BugPattern.LinkType;
-import com.google.errorprone.BugPattern.ProvidesFix;
-import com.google.errorprone.BugPattern.SeverityLevel;
-import com.google.errorprone.BugPattern.StandardTags;
 import com.google.errorprone.VisitorState;
 import com.google.errorprone.bugpatterns.BugChecker;
 import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
@@ -31,6 +31,7 @@ import java.util.Comparator;
 import java.util.Optional;
 import java.util.function.Function;
 import java.util.stream.Stream;
+import tech.picnic.errorprone.bugpatterns.util.SourceCode;
 
 /**
  * A {@link BugChecker} which flags {@code Comparator#comparing*} invocations that can be replaced
@@ -38,50 +39,89 @@ import java.util.stream.Stream;
  */
 // XXX: Add more documentation. Explain how this is useful in the face of refactoring to more
 // specific types.
-// XXX: Change this checker's name?
-// XXX: Introduce a companion checker (or Refaster template?) for
-// https://youtrack.jetbrains.com/issue/IDEA-185548.
 @AutoService(BugChecker.class)
 @BugPattern(
-    name = "PrimitiveComparison",
     summary =
         "Ensure invocations of `Comparator#comparing{,Double,Int,Long}` match the return type"
             + " of the provided function",
-    linkType = LinkType.NONE,
-    severity = SeverityLevel.WARNING,
-    tags = StandardTags.PERFORMANCE,
-    providesFix = ProvidesFix.REQUIRES_HUMAN_ATTENTION)
-public final class PrimitiveComparisonCheck extends BugChecker
-    implements MethodInvocationTreeMatcher {
+    linkType = NONE,
+    severity = WARNING,
+    tags = PERFORMANCE)
+public final class PrimitiveComparison extends BugChecker implements MethodInvocationTreeMatcher {
   private static final long serialVersionUID = 1L;
-  private static final Matcher<ExpressionTree> STATIC_MATCH = getStaticTargetMatcher();
-  private static final Matcher<ExpressionTree> INSTANCE_MATCH = getInstanceTargetMatcher();
+  private static final Matcher<ExpressionTree> STATIC_COMPARISON_METHOD =
+      anyOf(
+          staticMethod()
+              .onClass(Comparator.class.getName())
+              .namedAnyOf("comparingInt", "comparingLong", "comparingDouble"),
+          staticMethod()
+              .onClass(Comparator.class.getName())
+              .named("comparing")
+              .withParameters(Function.class.getName()));
+  private static final Matcher<ExpressionTree> INSTANCE_COMPARISON_METHOD =
+      anyOf(
+          instanceMethod()
+              .onDescendantOf(Comparator.class.getName())
+              .namedAnyOf("thenComparingInt", "thenComparingLong", "thenComparingDouble"),
+          instanceMethod()
+              .onDescendantOf(Comparator.class.getName())
+              .named("thenComparing")
+              .withParameters(Function.class.getName()));
 
   @Override
   public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
-    boolean isStatic = STATIC_MATCH.matches(tree, state);
-    if (!isStatic && !INSTANCE_MATCH.matches(tree, state)) {
+    boolean isStatic = STATIC_COMPARISON_METHOD.matches(tree, state);
+    if (!isStatic && !INSTANCE_COMPARISON_METHOD.matches(tree, state)) {
       return Description.NO_MATCH;
     }
 
     return getPotentiallyBoxedReturnType(tree.getArguments().get(0))
-        .flatMap(cmpType -> tryFix(tree, state, cmpType, isStatic))
+        .flatMap(cmpType -> attemptMethodInvocationReplacement(tree, cmpType, isStatic, state))
         .map(fix -> describeMatch(tree, fix))
         .orElse(Description.NO_MATCH);
   }
 
-  private static Optional<Fix> tryFix(
-      MethodInvocationTree tree, VisitorState state, Type cmpType, boolean isStatic) {
-    return Optional.ofNullable(ASTHelpers.getSymbol(tree))
-        .map(methodSymbol -> methodSymbol.getSimpleName().toString())
-        .flatMap(
-            actualMethodName ->
-                Optional.of(getPreferredMethod(state, cmpType, isStatic))
-                    .filter(not(actualMethodName::equals)))
-        .map(preferredMethodName -> suggestFix(tree, preferredMethodName, state));
+  private static Optional<Fix> attemptMethodInvocationReplacement(
+      MethodInvocationTree tree, Type cmpType, boolean isStatic, VisitorState state) {
+    String actualMethodName = ASTHelpers.getSymbol(tree).getSimpleName().toString();
+    String preferredMethodName = getPreferredMethod(cmpType, isStatic, state);
+    if (actualMethodName.equals(preferredMethodName)) {
+      return Optional.empty();
+    }
+
+    return Optional.of(
+        suggestFix(
+            tree, prefixTypeArgumentsIfRelevant(preferredMethodName, tree, cmpType, state), state));
   }
 
-  private static String getPreferredMethod(VisitorState state, Type cmpType, boolean isStatic) {
+  /**
+   * Prefixes the given method name with generic type parameters if it replaces a {@code
+   * Comparator#comparing{,Double,Long,Int}} method which also has generic type parameters.
+   *
+   * <p>Such type parameters are retained as they are likely required.
+   *
+   * <p>Note that any type parameter to {@code Comparator#thenComparing} is likely redundant, and in
+   * any case becomes obsolete once that method is replaced with {@code
+   * Comparator#thenComparing{Double,Long,Int}}. Conversion in the opposite direction does not
+   * require the introduction of a generic type parameter.
+   */
+  private static String prefixTypeArgumentsIfRelevant(
+      String preferredMethodName, MethodInvocationTree tree, Type cmpType, VisitorState state) {
+    if (tree.getTypeArguments().isEmpty() || preferredMethodName.startsWith("then")) {
+      return preferredMethodName;
+    }
+
+    String typeArguments =
+        Stream.concat(
+                Stream.of(SourceCode.treeToString(tree.getTypeArguments().get(0), state)),
+                Stream.of(cmpType.tsym.getSimpleName())
+                    .filter(u -> "comparing".equals(preferredMethodName)))
+            .collect(joining(", ", "<", ">"));
+
+    return typeArguments + preferredMethodName;
+  }
+
+  private static String getPreferredMethod(Type cmpType, boolean isStatic, VisitorState state) {
     Types types = state.getTypes();
     Symtab symtab = state.getSymtab();
 
@@ -116,9 +156,6 @@ public final class PrimitiveComparisonCheck extends BugChecker
     }
   }
 
-  // XXX: We drop explicitly specified generic type information. In case the number of type
-  // arguments before and after doesn't match, that's for the better. But if we e.g. replace
-  // `comparingLong` with `comparingInt`, then we should retain it.
   private static Fix suggestFix(
       MethodInvocationTree tree, String preferredMethodName, VisitorState state) {
     ExpressionTree expr = tree.getMethodSelect();
@@ -131,36 +168,9 @@ public final class PrimitiveComparisonCheck extends BugChecker
       case MEMBER_SELECT:
         MemberSelectTree ms = (MemberSelectTree) tree.getMethodSelect();
         return SuggestedFix.replace(
-            ms, Util.treeToString(ms.getExpression(), state) + '.' + preferredMethodName);
+            ms, SourceCode.treeToString(ms.getExpression(), state) + '.' + preferredMethodName);
       default:
         throw new VerifyException("Unexpected type of expression: " + expr.getKind());
     }
   }
-
-  private static Matcher<ExpressionTree> getStaticTargetMatcher() {
-    String clazz = Comparator.class.getName();
-    return anyMatch(
-        staticMethod()
-            .onClass(clazz)
-            .namedAnyOf("comparingInt", "comparingLong", "comparingDouble"),
-        staticMethod().onClass(clazz).named("comparing").withParameters(Function.class.getName()));
-  }
-
-  private static Matcher<ExpressionTree> getInstanceTargetMatcher() {
-    String clazz = Comparator.class.getName();
-    return anyMatch(
-        instanceMethod()
-            .onDescendantOf(clazz)
-            .namedAnyOf("thenComparingInt", "thenComparingLong", "thenComparingDouble"),
-        instanceMethod()
-            .onDescendantOf(clazz)
-            .named("thenComparing")
-            .withParameters(Function.class.getName()));
-  }
-
-  @SafeVarargs
-  @SuppressWarnings("varargs")
-  private static Matcher<ExpressionTree> anyMatch(Matcher<ExpressionTree>... matchers) {
-    return (ExpressionTree t, VisitorState s) -> Stream.of(matchers).anyMatch(m -> m.matches(t, s));
-  }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/RedundantStringConversion.java

@@ -1,8 +1,11 @@
 package tech.picnic.errorprone.bugpatterns;
 
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
 import static com.google.errorprone.matchers.Matchers.allOf;
 import static com.google.errorprone.matchers.Matchers.anyOf;
-import static com.google.errorprone.matchers.Matchers.isNonNull;
+import static com.google.errorprone.matchers.Matchers.isNonNullUsingDataflow;
 import static com.google.errorprone.matchers.Matchers.isSameType;
 import static com.google.errorprone.matchers.Matchers.isSubtypeOf;
 import static com.google.errorprone.matchers.Matchers.not;
@@ -12,10 +15,6 @@ import static com.google.errorprone.matchers.method.MethodMatchers.staticMethod;
 import com.google.auto.service.AutoService;
 import com.google.common.collect.Iterables;
 import com.google.errorprone.BugPattern;
-import com.google.errorprone.BugPattern.LinkType;
-import com.google.errorprone.BugPattern.ProvidesFix;
-import com.google.errorprone.BugPattern.SeverityLevel;
-import com.google.errorprone.BugPattern.StandardTags;
 import com.google.errorprone.ErrorProneFlags;
 import com.google.errorprone.VisitorState;
 import com.google.errorprone.bugpatterns.BugChecker;
@@ -42,18 +41,17 @@ import java.util.List;
 import java.util.Locale;
 import java.util.Objects;
 import java.util.Optional;
-import java.util.regex.Pattern;
+import tech.picnic.errorprone.bugpatterns.util.MethodMatcherFactory;
+import tech.picnic.errorprone.bugpatterns.util.SourceCode;
 
 /** A {@link BugChecker} which flags redundant explicit string conversions. */
 @AutoService(BugChecker.class)
 @BugPattern(
-    name = "RedundantStringConversion",
     summary = "Avoid redundant string conversions when possible",
-    linkType = LinkType.NONE,
-    severity = SeverityLevel.SUGGESTION,
-    tags = StandardTags.SIMPLIFICATION,
-    providesFix = ProvidesFix.REQUIRES_HUMAN_ATTENTION)
-public final class RedundantStringConversionCheck extends BugChecker
+    linkType = NONE,
+    severity = SUGGESTION,
+    tags = SIMPLIFICATION)
+public final class RedundantStringConversion extends BugChecker
     implements BinaryTreeMatcher, CompoundAssignmentTreeMatcher, MethodInvocationTreeMatcher {
   private static final long serialVersionUID = 1L;
   private static final String FLAG_PREFIX = "RedundantStringConversion:";
@@ -67,7 +65,8 @@ public final class RedundantStringConversionCheck extends BugChecker
   private static final Matcher<ExpressionTree> MARKER = isSubtypeOf("org.slf4j.Marker");
   private static final Matcher<ExpressionTree> STRING = isSameType(String.class);
   private static final Matcher<ExpressionTree> THROWABLE = isSubtypeOf(Throwable.class);
-  private static final Matcher<ExpressionTree> NON_NULL_STRING = allOf(STRING, isNonNull());
+  private static final Matcher<ExpressionTree> NON_NULL_STRING =
+      allOf(STRING, isNonNullUsingDataflow());
   private static final Matcher<ExpressionTree> NOT_FORMATTABLE =
       not(isSubtypeOf(Formattable.class));
   private static final Matcher<ExpressionTree> WELL_KNOWN_STRING_CONVERSION_METHODS =
@@ -129,47 +128,47 @@ public final class RedundantStringConversionCheck extends BugChecker
           instanceMethod().onDescendantOf(Formatter.class.getName()).named("format"),
           instanceMethod()
               .onDescendantOf(PrintStream.class.getName())
-              .withNameMatching(Pattern.compile("format|printf")),
+              .namedAnyOf("format", "printf"),
           instanceMethod()
               .onDescendantOf(PrintStream.class.getName())
-              .withNameMatching(Pattern.compile("print|println"))
+              .namedAnyOf("print", "println")
               .withParameters(Object.class.getName()),
           instanceMethod()
               .onDescendantOf(PrintWriter.class.getName())
-              .withNameMatching(Pattern.compile("format|printf")),
+              .namedAnyOf("format", "printf"),
           instanceMethod()
               .onDescendantOf(PrintWriter.class.getName())
-              .withNameMatching(Pattern.compile("print|println"))
+              .namedAnyOf("print", "println")
               .withParameters(Object.class.getName()),
           staticMethod()
               .onClass(Console.class.getName())
-              .withNameMatching(Pattern.compile("format|printf|readline|readPassword")));
+              .namedAnyOf("format", "printf", "readline", "readPassword"));
   private static final Matcher<ExpressionTree> GUAVA_GUARD_INVOCATION =
       anyOf(
           staticMethod()
               .onClass("com.google.common.base.Preconditions")
-              .withNameMatching(Pattern.compile("checkArgument|checkState|checkNotNull")),
+              .namedAnyOf("checkArgument", "checkState", "checkNotNull"),
           staticMethod()
               .onClass("com.google.common.base.Verify")
-              .withNameMatching(Pattern.compile("verify|verifyNotNull")));
+              .namedAnyOf("verify", "verifyNotNull"));
   private static final Matcher<ExpressionTree> SLF4J_LOGGER_INVOCATION =
       instanceMethod()
           .onDescendantOf("org.slf4j.Logger")
-          .withNameMatching(Pattern.compile("trace|debug|info|warn|error"));
+          .namedAnyOf("trace", "debug", "info", "warn", "error");
 
   private final Matcher<ExpressionTree> conversionMethodMatcher;
 
-  /** Instantiates the default {@link RedundantStringConversionCheck}. */
-  public RedundantStringConversionCheck() {
+  /** Instantiates the default {@link RedundantStringConversion}. */
+  public RedundantStringConversion() {
     this(ErrorProneFlags.empty());
   }
 
   /**
-   * Instantiates a customized {@link RedundantStringConversionCheck}.
+   * Instantiates a customized {@link RedundantStringConversion}.
    *
    * @param flags Any provided command line flags.
    */
-  public RedundantStringConversionCheck(ErrorProneFlags flags) {
+  public RedundantStringConversion(ErrorProneFlags flags) {
     conversionMethodMatcher = createConversionMethodMatcher(flags);
   }
 
@@ -191,11 +190,10 @@ public final class RedundantStringConversionCheck extends BugChecker
     ExpressionTree preferredRhs = trySimplify(rhs, state).orElse(rhs);
     if (STRING.matches(preferredRhs, state)) {
       tryFix(lhs, state, ANY_EXPR).ifPresent(fixes::add);
-      tryFix(rhs, state, ANY_EXPR).ifPresent(fixes::add);
     } else {
       tryFix(lhs, state, STRING).ifPresent(fixes::add);
-      tryFix(rhs, state, ANY_EXPR).ifPresent(fixes::add);
     }
+    tryFix(rhs, state, ANY_EXPR).ifPresent(fixes::add);
 
     return finalize(tree, fixes.stream().reduce(SuggestedFix.Builder::merge));
   }
@@ -329,7 +327,7 @@ public final class RedundantStringConversionCheck extends BugChecker
     return trySimplify(tree, state, filter)
         .map(
             replacement ->
-                SuggestedFix.builder().replace(tree, Util.treeToString(replacement, state)));
+                SuggestedFix.builder().replace(tree, SourceCode.treeToString(replacement, state)));
   }
 
   private Optional<ExpressionTree> trySimplify(
@@ -353,7 +351,7 @@ public final class RedundantStringConversionCheck extends BugChecker
       default:
         throw new IllegalStateException(
             "Cannot simplify method call with two or more arguments: "
-                + Util.treeToString(tree, state));
+                + SourceCode.treeToString(tree, state));
     }
   }
 
@@ -366,7 +364,7 @@ public final class RedundantStringConversionCheck extends BugChecker
     return Optional.of(methodInvocation.getMethodSelect())
         .filter(methodSelect -> methodSelect.getKind() == Kind.MEMBER_SELECT)
         .map(methodSelect -> ((MemberSelectTree) methodSelect).getExpression())
-        .filter(expr -> !"super".equals(Util.treeToString(expr, state)));
+        .filter(expr -> !"super".equals(SourceCode.treeToString(expr, state)));
   }
 
   private static Optional<ExpressionTree> trySimplifyUnaryMethod(

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/RefasterAnyOfUsage.java

@@ -0,0 +1,57 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+import static com.google.errorprone.matchers.method.MethodMatchers.staticMethod;
+
+import com.google.auto.service.AutoService;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.google.errorprone.refaster.Refaster;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.MethodInvocationTree;
+import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+
+/**
+ * A {@link BugChecker} which flags unnecessary {@link Refaster#anyOf(Object[])} usages.
+ *
+ * <p>Note that this logic can't be implemented as a Refaster template, as the {@link Refaster}
+ * class is treated specially.
+ */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "`Refaster#anyOf` should be passed at least two parameters",
+    linkType = NONE,
+    severity = SUGGESTION,
+    tags = SIMPLIFICATION)
+public final class RefasterAnyOfUsage extends BugChecker implements MethodInvocationTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Matcher<ExpressionTree> REFASTER_ANY_OF =
+      staticMethod().onClass(Refaster.class.getName()).named("anyOf");
+
+  @Override
+  public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    if (REFASTER_ANY_OF.matches(tree, state)) {
+      switch (tree.getArguments().size()) {
+        case 0:
+          // We can't safely fix this case; dropping the expression may produce non-compilable code.
+          return describeMatch(tree);
+        case 1:
+          return describeMatch(
+              tree,
+              SuggestedFix.replace(
+                  tree, SourceCode.treeToString(tree.getArguments().get(0), state)));
+        default:
+          /* Handled below. */
+      }
+    }
+
+    return Description.NO_MATCH;
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/RequestMappingAnnotation.java

@@ -0,0 +1,97 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
+import static com.google.errorprone.BugPattern.StandardTags.LIKELY_ERROR;
+import static com.google.errorprone.matchers.ChildMultiMatcher.MatchType.ALL;
+import static com.google.errorprone.matchers.ChildMultiMatcher.MatchType.AT_LEAST_ONE;
+import static com.google.errorprone.matchers.Matchers.annotations;
+import static com.google.errorprone.matchers.Matchers.anyOf;
+import static com.google.errorprone.matchers.Matchers.isSameType;
+import static com.google.errorprone.matchers.Matchers.isType;
+import static com.google.errorprone.matchers.Matchers.methodHasParameters;
+import static com.google.errorprone.matchers.Matchers.not;
+
+import com.google.auto.service.AutoService;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodTreeMatcher;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.sun.source.tree.MethodTree;
+import com.sun.source.tree.Tree;
+
+/**
+ * A {@link BugChecker} which flags {@code @RequestMapping} methods that have one or more parameters
+ * that appear to lack a relevant annotation.
+ *
+ * <p>Matched mappings are {@code @{Delete,Get,Patch,Post,Put,Request}Mapping}.
+ */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "Make sure all `@RequestMapping` method parameters are annotated",
+    linkType = NONE,
+    severity = WARNING,
+    tags = LIKELY_ERROR)
+public final class RequestMappingAnnotation extends BugChecker implements MethodTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final String ANN_PACKAGE_PREFIX = "org.springframework.web.bind.annotation.";
+  // XXX: Generalize this logic to fully support Spring meta-annotations, then update the class
+  // documentation.
+  private static final Matcher<Tree> HAS_MAPPING_ANNOTATION =
+      annotations(
+          AT_LEAST_ONE,
+          anyOf(
+              isType(ANN_PACKAGE_PREFIX + "DeleteMapping"),
+              isType(ANN_PACKAGE_PREFIX + "GetMapping"),
+              isType(ANN_PACKAGE_PREFIX + "PatchMapping"),
+              isType(ANN_PACKAGE_PREFIX + "PostMapping"),
+              isType(ANN_PACKAGE_PREFIX + "PutMapping"),
+              isType(ANN_PACKAGE_PREFIX + "RequestMapping")));
+  // XXX: Add other parameters as necessary. Also consider whether it makes sense to have WebMVC-
+  // and WebFlux-specific logic. See
+  // https://docs.spring.io/spring-framework/docs/current/reference/html/web.html#mvc-ann-arguments
+  // and
+  // https://docs.spring.io/spring-framework/docs/current/reference/html/web-reactive.html#webflux-ann-arguments.
+  private static final Matcher<MethodTree> LACKS_PARAMETER_ANNOTATION =
+      not(
+          methodHasParameters(
+              ALL,
+              anyOf(
+                  annotations(
+                      AT_LEAST_ONE,
+                      anyOf(
+                          isType(ANN_PACKAGE_PREFIX + "PathVariable"),
+                          isType(ANN_PACKAGE_PREFIX + "RequestAttribute"),
+                          isType(ANN_PACKAGE_PREFIX + "RequestBody"),
+                          isType(ANN_PACKAGE_PREFIX + "RequestHeader"),
+                          isType(ANN_PACKAGE_PREFIX + "RequestParam"))),
+                  isSameType("java.io.InputStream"),
+                  isSameType("java.time.ZoneId"),
+                  isSameType("java.util.Locale"),
+                  isSameType("java.util.TimeZone"),
+                  isSameType("javax.servlet.http.HttpServletRequest"),
+                  isSameType("javax.servlet.http.HttpServletResponse"),
+                  isSameType("org.springframework.http.HttpMethod"),
+                  isSameType("org.springframework.web.context.request.NativeWebRequest"),
+                  isSameType("org.springframework.web.context.request.WebRequest"),
+                  isSameType("org.springframework.web.server.ServerWebExchange"),
+                  isSameType("org.springframework.web.util.UriBuilder"),
+                  isSameType("org.springframework.web.util.UriComponentsBuilder"))));
+
+  @Override
+  public Description matchMethod(MethodTree tree, VisitorState state) {
+    // XXX: Auto-add `@RequestParam` where applicable.
+    // XXX: What about the `PurchasingProposerRequestParams` in POM? Implies `@RequestBody`?
+    // (Documentation doesn't mention this, IIUC.)
+    return HAS_MAPPING_ANNOTATION.matches(tree, state)
+            && LACKS_PARAMETER_ANNOTATION.matches(tree, state)
+        ? buildDescription(tree)
+            .setMessage(
+                "Not all parameters of this request mapping method are annotated; this may be a mistake. "
+                    + "If the unannotated parameters represent query string parameters, annotate them with `@RequestParam`.")
+            .build()
+        : Description.NO_MATCH;
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/RequestParamType.java

@@ -0,0 +1,44 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.ERROR;
+import static com.google.errorprone.BugPattern.StandardTags.LIKELY_ERROR;
+import static com.google.errorprone.matchers.ChildMultiMatcher.MatchType.AT_LEAST_ONE;
+import static com.google.errorprone.matchers.Matchers.allOf;
+import static com.google.errorprone.matchers.Matchers.annotations;
+import static com.google.errorprone.matchers.Matchers.anyOf;
+import static com.google.errorprone.matchers.Matchers.isSubtypeOf;
+import static com.google.errorprone.matchers.Matchers.isType;
+
+import com.google.auto.service.AutoService;
+import com.google.common.collect.ImmutableCollection;
+import com.google.common.collect.ImmutableMap;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.VariableTreeMatcher;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.sun.source.tree.VariableTree;
+
+/** A {@link BugChecker} which flags {@code @RequestParam} parameters with an unsupported type. */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "`@RequestParam` does not support `ImmutableCollection` and `ImmutableMap` subtypes",
+    linkType = NONE,
+    severity = ERROR,
+    tags = LIKELY_ERROR)
+public final class RequestParamType extends BugChecker implements VariableTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Matcher<VariableTree> HAS_UNSUPPORTED_REQUEST_PARAM =
+      allOf(
+          annotations(AT_LEAST_ONE, isType("org.springframework.web.bind.annotation.RequestParam")),
+          anyOf(isSubtypeOf(ImmutableCollection.class), isSubtypeOf(ImmutableMap.class)));
+
+  @Override
+  public Description matchVariable(VariableTree tree, VisitorState state) {
+    return HAS_UNSUPPORTED_REQUEST_PARAM.matches(tree, state)
+        ? describeMatch(tree)
+        : Description.NO_MATCH;
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/ScheduledTransactionTrace.java

@@ -0,0 +1,87 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.ERROR;
+import static com.google.errorprone.BugPattern.StandardTags.LIKELY_ERROR;
+import static com.google.errorprone.matchers.ChildMultiMatcher.MatchType.AT_LEAST_ONE;
+import static com.google.errorprone.matchers.Matchers.annotations;
+import static com.google.errorprone.matchers.Matchers.hasAnnotation;
+import static com.google.errorprone.matchers.Matchers.isType;
+
+import com.google.auto.common.AnnotationMirrors;
+import com.google.auto.service.AutoService;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Iterables;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.fixes.SuggestedFixes;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.google.errorprone.matchers.MultiMatcher;
+import com.google.errorprone.util.ASTHelpers;
+import com.sun.source.tree.AnnotationTree;
+import com.sun.source.tree.MethodTree;
+import com.sun.source.tree.Tree;
+
+/**
+ * A {@link BugChecker} which flags methods with Spring's {@code @Scheduled} annotation that lack
+ * New Relic Agent's {@code @Trace(dispatcher = true)}.
+ */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "Scheduled operation must start a new New Relic transaction",
+    linkType = NONE,
+    severity = ERROR,
+    tags = LIKELY_ERROR)
+public final class ScheduledTransactionTrace extends BugChecker implements MethodTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final String TRACE_ANNOTATION_FQCN = "com.newrelic.api.agent.Trace";
+  private static final Matcher<Tree> IS_SCHEDULED =
+      hasAnnotation("org.springframework.scheduling.annotation.Scheduled");
+  private static final MultiMatcher<Tree, AnnotationTree> TRACE_ANNOTATION =
+      annotations(AT_LEAST_ONE, isType(TRACE_ANNOTATION_FQCN));
+
+  @Override
+  public Description matchMethod(MethodTree tree, VisitorState state) {
+    if (!IS_SCHEDULED.matches(tree, state)) {
+      return Description.NO_MATCH;
+    }
+
+    ImmutableList<AnnotationTree> traceAnnotations =
+        TRACE_ANNOTATION.multiMatchResult(tree, state).matchingNodes();
+    if (traceAnnotations.isEmpty()) {
+      /* This method completely lacks the `@Trace` annotation; add it. */
+      return describeMatch(
+          tree,
+          SuggestedFix.builder()
+              .addImport(TRACE_ANNOTATION_FQCN)
+              .prefixWith(tree, "@Trace(dispatcher = true)")
+              .build());
+    }
+
+    AnnotationTree traceAnnotation = Iterables.getOnlyElement(traceAnnotations);
+    if (isCorrectAnnotation(traceAnnotation)) {
+      return Description.NO_MATCH;
+    }
+
+    /*
+     * The `@Trace` annotation is present but does not specify `dispatcher = true`. Add or update
+     * the `dispatcher` annotation element.
+     */
+    return describeMatch(
+        traceAnnotation,
+        SuggestedFixes.updateAnnotationArgumentValues(
+                traceAnnotation, state, "dispatcher", ImmutableList.of("true"))
+            .build());
+  }
+
+  private static boolean isCorrectAnnotation(AnnotationTree traceAnnotation) {
+    return Boolean.TRUE.equals(
+        AnnotationMirrors.getAnnotationValue(
+                ASTHelpers.getAnnotationMirror(traceAnnotation), "dispatcher")
+            .getValue());
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/Slf4jLogStatement.java

@@ -1,16 +1,15 @@
 package tech.picnic.errorprone.bugpatterns;
 
 import static com.google.common.base.Verify.verify;
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
+import static com.google.errorprone.BugPattern.StandardTags.LIKELY_ERROR;
 import static com.google.errorprone.matchers.Matchers.isSubtypeOf;
 import static com.google.errorprone.matchers.method.MethodMatchers.instanceMethod;
 
 import com.google.auto.service.AutoService;
 import com.google.common.base.Splitter;
 import com.google.errorprone.BugPattern;
-import com.google.errorprone.BugPattern.LinkType;
-import com.google.errorprone.BugPattern.ProvidesFix;
-import com.google.errorprone.BugPattern.SeverityLevel;
-import com.google.errorprone.BugPattern.StandardTags;
 import com.google.errorprone.VisitorState;
 import com.google.errorprone.bugpatterns.BugChecker;
 import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
@@ -23,7 +22,7 @@ import com.sun.source.tree.MethodInvocationTree;
 import com.sun.source.tree.Tree.Kind;
 import java.util.List;
 import java.util.Optional;
-import java.util.regex.Pattern;
+import tech.picnic.errorprone.bugpatterns.util.SourceCode;
 
 /** A {@link BugChecker} which flags SLF4J usages that are likely to be in error. */
 // XXX: The special-casing of Throwable applies only to SLF4J 1.6.0+; see
@@ -33,21 +32,18 @@ import java.util.regex.Pattern;
 // preconditions, ...
 @AutoService(BugChecker.class)
 @BugPattern(
-    name = "Slf4jLogStatement",
     summary = "Make sure SLF4J log statements contain proper placeholders with matching arguments",
-    linkType = LinkType.NONE,
-    severity = SeverityLevel.WARNING,
-    tags = StandardTags.LIKELY_ERROR,
-    providesFix = ProvidesFix.REQUIRES_HUMAN_ATTENTION)
-public final class Slf4jLogStatementCheck extends BugChecker
-    implements MethodInvocationTreeMatcher {
+    linkType = NONE,
+    severity = WARNING,
+    tags = LIKELY_ERROR)
+public final class Slf4jLogStatement extends BugChecker implements MethodInvocationTreeMatcher {
   private static final long serialVersionUID = 1L;
   private static final Matcher<ExpressionTree> MARKER = isSubtypeOf("org.slf4j.Marker");
   private static final Matcher<ExpressionTree> THROWABLE = isSubtypeOf(Throwable.class);
   private static final Matcher<ExpressionTree> SLF4J_LOGGER_INVOCATION =
       instanceMethod()
           .onDescendantOf("org.slf4j.Logger")
-          .withNameMatching(Pattern.compile("trace|debug|info|warn|error"));
+          .namedAnyOf("trace", "debug", "info", "warn", "error");
 
   @Override
   public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
@@ -117,7 +113,7 @@ public final class Slf4jLogStatementCheck extends BugChecker
        * replaced at this usage site.
        */
       description.addFix(
-          SuggestedFix.replace(tree, Util.treeToString(tree, state).replace("%s", "{}")));
+          SuggestedFix.replace(tree, SourceCode.treeToString(tree, state).replace("%s", "{}")));
     }
 
     return false;

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/SpringMvcAnnotation.java

@@ -1,6 +1,10 @@
 package tech.picnic.errorprone.bugpatterns;
 
 import static com.google.common.base.Verify.verify;
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+import static java.util.function.Predicate.not;
 import static java.util.stream.Collectors.joining;
 
 import com.google.auto.service.AutoService;
@@ -8,10 +12,6 @@ import com.google.common.base.VerifyException;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.errorprone.BugPattern;
-import com.google.errorprone.BugPattern.LinkType;
-import com.google.errorprone.BugPattern.ProvidesFix;
-import com.google.errorprone.BugPattern.SeverityLevel;
-import com.google.errorprone.BugPattern.StandardTags;
 import com.google.errorprone.VisitorState;
 import com.google.errorprone.bugpatterns.BugChecker;
 import com.google.errorprone.bugpatterns.BugChecker.AnnotationTreeMatcher;
@@ -25,6 +25,8 @@ import com.sun.source.tree.MemberSelectTree;
 import com.sun.source.tree.NewArrayTree;
 import com.sun.source.tree.Tree.Kind;
 import java.util.Optional;
+import tech.picnic.errorprone.bugpatterns.util.AnnotationAttributeMatcher;
+import tech.picnic.errorprone.bugpatterns.util.SourceCode;
 
 /**
  * A {@link BugChecker} which flags {@code @RequestMapping} annotations that can be written more
@@ -32,14 +34,12 @@ import java.util.Optional;
  */
 @AutoService(BugChecker.class)
 @BugPattern(
-    name = "SpringMvcAnnotation",
     summary =
         "Prefer the conciseness of `@{Get,Put,Post,Delete,Patch}Mapping` over `@RequestMapping`",
-    linkType = LinkType.NONE,
-    severity = SeverityLevel.SUGGESTION,
-    tags = StandardTags.SIMPLIFICATION,
-    providesFix = ProvidesFix.REQUIRES_HUMAN_ATTENTION)
-public final class SpringMvcAnnotationCheck extends BugChecker implements AnnotationTreeMatcher {
+    linkType = NONE,
+    severity = SUGGESTION,
+    tags = SIMPLIFICATION)
+public final class SpringMvcAnnotation extends BugChecker implements AnnotationTreeMatcher {
   private static final long serialVersionUID = 1L;
   private static final String ANN_PACKAGE_PREFIX = "org.springframework.web.bind.annotation.";
   private static final AnnotationAttributeMatcher ARGUMENT_SELECTOR =
@@ -70,7 +70,7 @@ public final class SpringMvcAnnotationCheck extends BugChecker implements Annota
       AnnotationTree tree, ExpressionTree arg, VisitorState state) {
     return extractUniqueMethod(arg, state)
         .map(REPLACEMENTS::get)
-        .map(newAnnotation -> replaceAnnotation(tree, arg, newAnnotation));
+        .map(newAnnotation -> replaceAnnotation(tree, arg, newAnnotation, state));
   }
 
   private static Optional<String> extractUniqueMethod(ExpressionTree arg, VisitorState state) {
@@ -93,7 +93,7 @@ public final class SpringMvcAnnotationCheck extends BugChecker implements Annota
   private static String extractMethod(ExpressionTree expr, VisitorState state) {
     switch (expr.getKind()) {
       case IDENTIFIER:
-        return Util.treeToString(expr, state);
+        return SourceCode.treeToString(expr, state);
       case MEMBER_SELECT:
         return ((MemberSelectTree) expr).getIdentifier().toString();
       default:
@@ -102,11 +102,11 @@ public final class SpringMvcAnnotationCheck extends BugChecker implements Annota
   }
 
   private static Fix replaceAnnotation(
-      AnnotationTree tree, ExpressionTree arg, String newAnnotation) {
+      AnnotationTree tree, ExpressionTree argToRemove, String newAnnotation, VisitorState state) {
     String newArguments =
         tree.getArguments().stream()
-            .filter(a -> !a.equals(arg))
-            .map(Object::toString)
+            .filter(not(argToRemove::equals))
+            .map(arg -> SourceCode.treeToString(arg, state))
             .collect(joining(", "));
 
     return SuggestedFix.builder()

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/StaticImport.java

@@ -0,0 +1,257 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+import static java.util.Objects.requireNonNull;
+
+import com.google.auto.service.AutoService;
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.ImmutableSetMultimap;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MemberSelectTreeMatcher;
+import com.google.errorprone.bugpatterns.StaticImports;
+import com.google.errorprone.bugpatterns.StaticImports.StaticImportInfo;
+import com.google.errorprone.fixes.Fix;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.fixes.SuggestedFixes;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.util.ASTHelpers;
+import com.sun.source.tree.MemberSelectTree;
+import com.sun.source.tree.MethodInvocationTree;
+import com.sun.source.tree.Tree;
+import com.sun.tools.javac.code.Type;
+import java.util.Optional;
+
+/**
+ * A {@link BugChecker} which flags methods and constants that can and should be statically
+ * imported.
+ */
+// XXX: Tricky cases:
+// - `org.springframework.http.HttpStatus` (not always an improvement, and `valueOf` must
+//    certainly be excluded)
+// - `com.google.common.collect.Tables`
+// - `ch.qos.logback.classic.Level.{DEBUG, ERROR, INFO, TRACE, WARN"}`
+// XXX: Also introduce a check which disallows static imports of certain methods. Candidates:
+// - `com.google.common.base.Strings`
+// - `java.util.Optional.empty`
+// - `java.util.Locale.ROOT`
+// - `ZoneOffset.ofHours` and other `ofXXX`-style methods.
+// - `java.time.Clock`.
+// - Several other `java.time` classes.
+// - Likely any of `*.{ZERO, ONE, MIX, MAX, MIN_VALUE, MAX_VALUE}`.
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "Identifier should be statically imported",
+    linkType = NONE,
+    severity = SUGGESTION,
+    tags = SIMPLIFICATION)
+public final class StaticImport extends BugChecker implements MemberSelectTreeMatcher {
+  private static final long serialVersionUID = 1L;
+
+  /**
+   * Types whose members should be statically imported, unless exempted by {@link
+   * #STATIC_IMPORT_EXEMPTED_MEMBERS} or {@link #STATIC_IMPORT_EXEMPTED_IDENTIFIERS}.
+   */
+  @VisibleForTesting
+  static final ImmutableSet<String> STATIC_IMPORT_CANDIDATE_TYPES =
+      ImmutableSet.of(
+          "com.google.common.base.Preconditions",
+          "com.google.common.base.Predicates",
+          "com.google.common.base.Verify",
+          "com.google.common.collect.MoreCollectors",
+          "com.google.errorprone.BugPattern.LinkType",
+          "com.google.errorprone.BugPattern.SeverityLevel",
+          "com.google.errorprone.BugPattern.StandardTags",
+          "com.google.errorprone.matchers.Matchers",
+          "com.google.errorprone.refaster.ImportPolicy",
+          "com.mongodb.client.model.Accumulators",
+          "com.mongodb.client.model.Aggregates",
+          "com.mongodb.client.model.Filters",
+          "com.mongodb.client.model.Indexes",
+          "com.mongodb.client.model.Projections",
+          "com.mongodb.client.model.Sorts",
+          "com.mongodb.client.model.Updates",
+          "java.nio.charset.StandardCharsets",
+          "java.util.Collections",
+          "java.util.Comparator",
+          "java.util.Map.Entry",
+          "java.util.regex.Pattern",
+          "java.util.stream.Collectors",
+          "org.assertj.core.api.Assertions",
+          "org.assertj.core.api.InstanceOfAssertFactories",
+          "org.assertj.core.api.SoftAssertions",
+          "org.assertj.core.data.Offset",
+          "org.assertj.core.groups.Tuple",
+          "org.hamcrest.Matchers",
+          "org.hamcrest.text.MatchesPattern",
+          "org.hibernate.validator.testutil.ConstraintViolationAssert",
+          "org.junit.jupiter.api.Assertions",
+          "org.mockito.AdditionalAnswers",
+          "org.mockito.Answers",
+          "org.mockito.ArgumentMatchers",
+          "org.mockito.Mockito",
+          "org.springframework.boot.test.context.SpringBootTest.WebEnvironment",
+          "org.springframework.format.annotation.DateTimeFormat.ISO",
+          "org.springframework.http.HttpHeaders",
+          "org.springframework.http.HttpMethod",
+          "org.springframework.http.MediaType",
+          "org.testng.Assert",
+          "reactor.function.TupleUtils");
+
+  /** Type members that should be statically imported. */
+  @VisibleForTesting
+  static final ImmutableSetMultimap<String, String> STATIC_IMPORT_CANDIDATE_MEMBERS =
+      ImmutableSetMultimap.<String, String>builder()
+          .putAll(
+              "com.google.common.collect.ImmutableListMultimap",
+              "flatteningToImmutableListMultimap",
+              "toImmutableListMultimap")
+          .put("com.google.common.collect.ImmutableList", "toImmutableList")
+          .put("com.google.common.collect.ImmutableMap", "toImmutableMap")
+          .put("com.google.common.collect.ImmutableMultiset", "toImmutableMultiset")
+          .put("com.google.common.collect.ImmutableRangeSet", "toImmutableRangeSet")
+          .putAll(
+              "com.google.common.collect.ImmutableSetMultimap",
+              "flatteningToImmutableSetMultimap",
+              "toImmutableSetMultimap")
+          .put("com.google.common.collect.ImmutableSet", "toImmutableSet")
+          .put("com.google.common.collect.ImmutableSortedMap", "toImmutableSortedMap")
+          .put("com.google.common.collect.ImmutableSortedMultiset", "toImmutableSortedMultiset")
+          .put("com.google.common.collect.ImmutableSortedSet", "toImmutableSortedSet")
+          .put("com.google.common.collect.ImmutableTable", "toImmutableTable")
+          .put("com.google.common.collect.Sets", "toImmutableEnumSet")
+          .put("com.google.common.base.Functions", "identity")
+          .put("java.time.ZoneOffset", "UTC")
+          .put("java.util.function.Function", "identity")
+          .put("java.util.function.Predicate", "not")
+          .put("java.util.UUID", "randomUUID")
+          .put("org.junit.jupiter.params.provider.Arguments", "arguments")
+          .putAll(
+              "java.util.Objects",
+              "checkIndex",
+              "checkFromIndexSize",
+              "checkFromToIndex",
+              "requireNonNull",
+              "requireNonNullElse",
+              "requireNonNullElseGet")
+          .putAll("com.google.common.collect.Comparators", "emptiesFirst", "emptiesLast")
+          .build();
+
+  /**
+   * Type members that should never be statically imported.
+   *
+   * <p>Identifiers listed by {@link #STATIC_IMPORT_EXEMPTED_IDENTIFIERS} should be omitted from
+   * this collection.
+   */
+  // XXX: Perhaps the set of exempted `java.util.Collections` methods is too strict. For now any
+  // method name that could be considered "too vague" or could conceivably mean something else in a
+  // specific context is left out.
+  @VisibleForTesting
+  static final ImmutableSetMultimap<String, String> STATIC_IMPORT_EXEMPTED_MEMBERS =
+      ImmutableSetMultimap.<String, String>builder()
+          .put("com.mongodb.client.model.Filters", "empty")
+          .putAll(
+              "java.util.Collections",
+              "addAll",
+              "copy",
+              "fill",
+              "list",
+              "max",
+              "min",
+              "nCopies",
+              "rotate",
+              "sort",
+              "swap")
+          .putAll("java.util.regex.Pattern", "compile", "matches", "quote")
+          .put("org.springframework.http.MediaType", "ALL")
+          .build();
+
+  /**
+   * Identifiers that should never be statically imported.
+   *
+   * <p>This should be a superset of the identifiers flagged by {@link
+   * com.google.errorprone.bugpatterns.BadImport}.
+   */
+  @VisibleForTesting
+  static final ImmutableSet<String> STATIC_IMPORT_EXEMPTED_IDENTIFIERS =
+      ImmutableSet.of(
+          "builder",
+          "create",
+          "copyOf",
+          "from",
+          "getDefaultInstance",
+          "INSTANCE",
+          "newBuilder",
+          "of",
+          "valueOf");
+
+  @Override
+  public Description matchMemberSelect(MemberSelectTree tree, VisitorState state) {
+    if (!isCandidateContext(state) || !isCandidate(tree)) {
+      return Description.NO_MATCH;
+    }
+
+    StaticImportInfo importInfo = StaticImports.tryCreate(tree, state);
+    if (importInfo == null) {
+      return Description.NO_MATCH;
+    }
+
+    return getCandidateSimpleName(importInfo)
+        .flatMap(n -> tryStaticImport(tree, importInfo.canonicalName() + '.' + n, n, state))
+        .map(fix -> describeMatch(tree, fix))
+        .orElse(Description.NO_MATCH);
+  }
+
+  private static boolean isCandidateContext(VisitorState state) {
+    Tree parentTree =
+        requireNonNull(state.getPath().getParentPath(), "MemberSelectTree lacks enclosing node")
+            .getLeaf();
+    switch (parentTree.getKind()) {
+      case IMPORT:
+      case MEMBER_SELECT:
+        return false;
+      case METHOD_INVOCATION:
+        return ((MethodInvocationTree) parentTree).getTypeArguments().isEmpty();
+      default:
+        return true;
+    }
+  }
+
+  private static boolean isCandidate(MemberSelectTree tree) {
+    String identifier = tree.getIdentifier().toString();
+    if (STATIC_IMPORT_EXEMPTED_IDENTIFIERS.contains(identifier)) {
+      return false;
+    }
+
+    Type type = ASTHelpers.getType(tree.getExpression());
+    return type != null
+        && !STATIC_IMPORT_EXEMPTED_MEMBERS.containsEntry(type.toString(), identifier);
+  }
+
+  private static Optional<String> getCandidateSimpleName(StaticImportInfo importInfo) {
+    String canonicalName = importInfo.canonicalName();
+    return importInfo
+        .simpleName()
+        .toJavaUtil()
+        .filter(
+            name ->
+                STATIC_IMPORT_CANDIDATE_TYPES.contains(canonicalName)
+                    || STATIC_IMPORT_CANDIDATE_MEMBERS.containsEntry(canonicalName, name));
+  }
+
+  private static Optional<Fix> tryStaticImport(
+      MemberSelectTree tree, String fullyQualifiedName, String simpleName, VisitorState state) {
+    SuggestedFix.Builder fix = SuggestedFix.builder().replace(tree, simpleName);
+
+    if (!simpleName.equals(SuggestedFixes.qualifyStaticImport(fullyQualifiedName, fix, state))) {
+      /* Statically importing this symbol would clash with an existing import. */
+      return Optional.empty();
+    }
+
+    return Optional.of(fix.build());
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/TimeZoneUsage.java

@@ -0,0 +1,69 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
+import static com.google.errorprone.BugPattern.StandardTags.FRAGILE_CODE;
+import static com.google.errorprone.matchers.Matchers.allOf;
+import static com.google.errorprone.matchers.Matchers.anyOf;
+import static com.google.errorprone.matchers.Matchers.enclosingClass;
+import static com.google.errorprone.matchers.Matchers.instanceMethod;
+import static com.google.errorprone.matchers.Matchers.isSubtypeOf;
+import static com.google.errorprone.matchers.Matchers.not;
+import static com.google.errorprone.matchers.Matchers.staticMethod;
+
+import com.google.auto.service.AutoService;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.MethodInvocationTree;
+import java.time.Clock;
+import java.time.Instant;
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.time.LocalTime;
+
+/** A {@link BugChecker} which flags illegal time-zone related operations. */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary =
+        "Derive the current time from an existing `Clock` Spring bean, and don't rely on a `Clock`'s time zone",
+    linkType = NONE,
+    severity = WARNING,
+    tags = FRAGILE_CODE)
+public final class TimeZoneUsage extends BugChecker implements MethodInvocationTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Matcher<ExpressionTree> BANNED_TIME_METHOD =
+      anyOf(
+          allOf(
+              instanceMethod()
+                  .onDescendantOf(Clock.class.getName())
+                  .namedAnyOf("getZone", "withZone"),
+              not(enclosingClass(isSubtypeOf(Clock.class)))),
+          staticMethod()
+              .onClass(Clock.class.getName())
+              .namedAnyOf(
+                  "system",
+                  "systemDefaultZone",
+                  "systemUTC",
+                  "tickMillis",
+                  "tickMinutes",
+                  "tickSeconds"),
+          staticMethod()
+              .onClassAny(
+                  LocalDate.class.getName(),
+                  LocalDateTime.class.getName(),
+                  LocalTime.class.getName())
+              .named("now"),
+          staticMethod().onClassAny(Instant.class.getName()).named("now").withNoParameters());
+
+  @Override
+  public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    return BANNED_TIME_METHOD.matches(tree, state)
+        ? buildDescription(tree).build()
+        : Description.NO_MATCH;
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/package-info.java

@@ -1,7 +1,4 @@
 /** Picnic Error Prone Contrib checks. */
-@CheckReturnValue
-@ParametersAreNonnullByDefault
+@com.google.errorprone.annotations.CheckReturnValue
+@javax.annotation.ParametersAreNonnullByDefault
 package tech.picnic.errorprone.bugpatterns;
-
-import com.google.errorprone.annotations.CheckReturnValue;
-import javax.annotation.ParametersAreNonnullByDefault;

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/util/AnnotationAttributeMatcher.java

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.bugpatterns;
+package tech.picnic.errorprone.bugpatterns.util;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.HashMultimap;
@@ -21,13 +21,14 @@ import java.util.stream.Stream;
 // XXX: Redefine using auto-value
 // XXX: Document design decision that the project stays as close as possible to Error Prone.
 //      ^ ... and *therefore* uses Google Auto Value rather than Immutables.org.
+// XXX: Make this class implement the `MultiMatcher` interface.
 /**
  * A matcher of (annotation, attribute) pairs.
  *
  * <p>This class allows one to define a whitelist or blacklist of annotations or their attributes.
  * Annotations are identified by their fully qualified name.
  */
-final class AnnotationAttributeMatcher implements Serializable {
+public final class AnnotationAttributeMatcher implements Serializable {
   private static final long serialVersionUID = 1L;
 
   private final boolean complement;
@@ -58,7 +59,7 @@ final class AnnotationAttributeMatcher implements Serializable {
    * @param exclusions The listed annotations or annotation attributes are not matched.
    * @return A non-{@code null} {@link AnnotationAttributeMatcher}.
    */
-  static AnnotationAttributeMatcher create(
+  public static AnnotationAttributeMatcher create(
       Optional<? extends List<String>> inclusions, Iterable<String> exclusions) {
     Set<String> includedWholeTypes = new HashSet<>();
     Set<String> excludedWholeTypes = new HashSet<>();
@@ -88,7 +89,6 @@ final class AnnotationAttributeMatcher implements Serializable {
       int hash = entry.indexOf('#');
       if (hash < 0) {
         wholeTypes.add(entry);
-
       } else {
         String annotationType = entry.substring(0, hash);
         String attribute = entry.substring(hash + 1);
@@ -97,7 +97,13 @@ final class AnnotationAttributeMatcher implements Serializable {
     }
   }
 
-  Stream<? extends ExpressionTree> extractMatchingArguments(AnnotationTree tree) {
+  /**
+   * Returns the subset of arguments of the given {@link AnnotationTree} matched by this instance.
+   *
+   * @param tree The annotation AST node to be inspected.
+   * @return Any matching annotation arguments.
+   */
+  public Stream<? extends ExpressionTree> extractMatchingArguments(AnnotationTree tree) {
     Type type = ASTHelpers.getType(tree.getAnnotationType());
     if (type == null) {
       return Stream.empty();

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/util/JavaKeywords.java

@@ -0,0 +1,129 @@
+package tech.picnic.errorprone.bugpatterns.util;
+
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Sets;
+
+/** Utility class that can be used to identify reserved keywords of the Java language. */
+public final class JavaKeywords {
+  /**
+   * List of all reserved keywords in the Java language.
+   *
+   * @see <a href="https://docs.oracle.com/javase/specs/jls/se17/html/jls-3.html#jls-3.9">JDK 17 JLS
+   *     section 3.9: Keywords</a>
+   */
+  private static final ImmutableSet<String> RESERVED_KEYWORDS =
+      ImmutableSet.of(
+          "_",
+          "abstract",
+          "assert",
+          "boolean",
+          "break",
+          "byte",
+          "case",
+          "catch",
+          "char",
+          "class",
+          "const",
+          "continue",
+          "default",
+          "do",
+          "double",
+          "else",
+          "enum",
+          "extends",
+          "final",
+          "finally",
+          "float",
+          "for",
+          "goto",
+          "if",
+          "implements",
+          "import",
+          "instanceof",
+          "int",
+          "interface",
+          "long",
+          "native",
+          "new",
+          "package",
+          "private",
+          "protected",
+          "public",
+          "return",
+          "short",
+          "static",
+          "strictfp",
+          "super",
+          "switch",
+          "synchronized",
+          "this",
+          "throw",
+          "throws",
+          "transient",
+          "try",
+          "void",
+          "volatile",
+          "while");
+
+  /**
+   * List of all contextual keywords in the Java language.
+   *
+   * @see <a href="https://docs.oracle.com/javase/specs/jls/se17/html/jls-3.html#jls-3.9">JDK 17 JLS
+   *     section 3.9: Keywords</a>
+   */
+  private static final ImmutableSet<String> CONTEXTUAL_KEYWORDS =
+      ImmutableSet.of(
+          "exports",
+          "module",
+          "non-sealed",
+          "open",
+          "opens",
+          "permits",
+          "provides",
+          "record",
+          "requires",
+          "sealed",
+          "to",
+          "transitive",
+          "uses",
+          "var",
+          "with",
+          "yield");
+
+  /** List of all keywords in the Java language. */
+  private static final ImmutableSet<String> ALL_KEYWORDS =
+      Sets.union(RESERVED_KEYWORDS, CONTEXTUAL_KEYWORDS).immutableCopy();
+
+  private JavaKeywords() {}
+
+  /**
+   * Tells whether the given string is a reserved keyword in the Java language.
+   *
+   * @param str The string of interest.
+   * @return {@code true} if the given string is a reserved keyword in the Java language.
+   */
+  public static boolean isReservedKeyword(String str) {
+    return RESERVED_KEYWORDS.contains(str);
+  }
+
+  /**
+   * Tells whether the given string is a contextual keyword in the Java language.
+   *
+   * @param str The string of interest.
+   * @return {@code true} if the given string is a contextual keyword in the Java language.
+   */
+  public static boolean isContextualKeyword(String str) {
+    return CONTEXTUAL_KEYWORDS.contains(str);
+  }
+
+  /**
+   * Tells whether the given string is a reserved or contextual keyword in the Java language.
+   *
+   * @param str The string of interest.
+   * @return {@code true} if the given string is a reserved or contextual keyword in the Java
+   *     language.
+   */
+  public static boolean isKeyword(String str) {
+    return ALL_KEYWORDS.contains(str);
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/util/MethodMatcherFactory.java

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.bugpatterns;
+package tech.picnic.errorprone.bugpatterns.util;
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.collect.ImmutableSet.toImmutableSet;
@@ -15,13 +15,20 @@ import java.util.regex.Pattern;
 /** A method invocation expression {@link Matcher} factory. */
 // XXX: Document better. The expressions accepted here could also be defined using `MethodMatchers`.
 // So explain why this class is still useful.
-final class MethodMatcherFactory {
+public final class MethodMatcherFactory {
   private static final Splitter ARGUMENT_TYPE_SPLITTER =
       Splitter.on(',').trimResults().omitEmptyStrings();
   private static final Pattern METHOD_SIGNATURE =
       Pattern.compile("([^\\s#(,)]+)#([^\\s#(,)]+)\\(((?:[^\\s#(,)]+(?:,[^\\s#(,)]+)*)?)\\)");
 
-  Matcher<ExpressionTree> create(Collection<String> signatures) {
+  /**
+   * Creates a {@link Matcher} of methods with any of the given signatures.
+   *
+   * @param signatures The method signatures of interest.
+   * @return A new {@link Matcher} which accepts invocation expressions of any method identified by
+   *     the given signatures.
+   */
+  public Matcher<ExpressionTree> create(Collection<String> signatures) {
     return anyOf(
         signatures.stream()
             .map(MethodMatcherFactory::createMethodMatcher)

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/util/SourceCode.java

@@ -1,19 +1,26 @@
-package tech.picnic.errorprone.bugpatterns;
+package tech.picnic.errorprone.bugpatterns.util;
 
 import com.google.errorprone.VisitorState;
 import com.sun.source.tree.Tree;
 
+/**
+ * A collection of Error Prone utility methods for dealing with the source code representation of
+ * AST nodes.
+ */
 // XXX: Can we locate this code in a better place? Maybe contribute it upstream?
-final class Util {
-  private Util() {}
+public final class SourceCode {
+  private SourceCode() {}
 
   /**
    * Returns a string representation of the given {@link Tree}, preferring the original source code
    * (if available) over its prettified representation.
    *
+   * @param tree The AST node of interest.
+   * @param state A {@link VisitorState} describing the context in which the given {@link Tree} is
+   *     found.
    * @return A non-{@code null} string.
    */
-  static String treeToString(Tree tree, VisitorState state) {
+  public static String treeToString(Tree tree, VisitorState state) {
     String src = state.getSourceForNode(tree);
     return src != null ? src : tree.toString();
   }

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/util/package-info.java

@@ -0,0 +1,4 @@
+/** Auxiliary utilities for use by Error Prone checks. */
+@com.google.errorprone.annotations.CheckReturnValue
+@javax.annotation.ParametersAreNonnullByDefault
+package tech.picnic.errorprone.bugpatterns.util;

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/AssertJBigDecimalTemplates.java

@@ -8,13 +8,22 @@ import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import java.math.BigDecimal;
 import org.assertj.core.api.AbstractBigDecimalAssert;
+import org.assertj.core.api.BigDecimalAssert;
 
-// XXX: If we add a rule which drops unnecessary `L` suffixes from literal longs, then the `0L`/`1L`
-// cases below can go.
+/**
+ * Refaster templates related to AssertJ assertions over {@link BigDecimal}s.
+ *
+ * <p>Note that, contrary to collections of Refaster templates for other {@link
+ * org.assertj.core.api.NumberAssert} subtypes, these templates do not rewrite to/from {@link
+ * BigDecimalAssert#isEqualTo(Object)} and {@link BigDecimalAssert#isNotEqualTo(Object)}. This is
+ * because {@link BigDecimal#equals(Object)} considers not only the numeric value of compared
+ * instances, but also their scale. As a result various seemingly straightforward transformations
+ * would actually subtly change the assertion's semantics.
+ */
 final class AssertJBigDecimalTemplates {
   private AssertJBigDecimalTemplates() {}
 
-  static final class AbstractBigDecimalAssertIsEqualTo {
+  static final class AbstractBigDecimalAssertIsEqualByComparingTo {
     @BeforeTemplate
     AbstractBigDecimalAssert<?> before(AbstractBigDecimalAssert<?> bigDecimalAssert, BigDecimal n) {
       return Refaster.anyOf(
@@ -24,11 +33,11 @@ final class AssertJBigDecimalTemplates {
 
     @AfterTemplate
     AbstractBigDecimalAssert<?> after(AbstractBigDecimalAssert<?> bigDecimalAssert, BigDecimal n) {
-      return bigDecimalAssert.isEqualTo(n);
+      return bigDecimalAssert.isEqualByComparingTo(n);
     }
   }
 
-  static final class AbstractBigDecimalAssertIsNotEqualTo {
+  static final class AbstractBigDecimalAssertIsNotEqualByComparingTo {
     @BeforeTemplate
     AbstractBigDecimalAssert<?> before(AbstractBigDecimalAssert<?> bigDecimalAssert, BigDecimal n) {
       return Refaster.anyOf(
@@ -38,52 +47,7 @@ final class AssertJBigDecimalTemplates {
 
     @AfterTemplate
     AbstractBigDecimalAssert<?> after(AbstractBigDecimalAssert<?> bigDecimalAssert, BigDecimal n) {
-      return bigDecimalAssert.isNotEqualTo(n);
-    }
-  }
-
-  static final class AbstractBigDecimalAssertIsZero {
-    @BeforeTemplate
-    AbstractBigDecimalAssert<?> before(AbstractBigDecimalAssert<?> bigDecimalAssert) {
-      return Refaster.anyOf(
-          bigDecimalAssert.isZero(),
-          bigDecimalAssert.isEqualTo(0L),
-          bigDecimalAssert.isEqualTo(BigDecimal.ZERO));
-    }
-
-    @AfterTemplate
-    AbstractBigDecimalAssert<?> after(AbstractBigDecimalAssert<?> bigDecimalAssert) {
-      return bigDecimalAssert.isEqualTo(0);
-    }
-  }
-
-  static final class AbstractBigDecimalAssertIsNotZero {
-    @BeforeTemplate
-    AbstractBigDecimalAssert<?> before(AbstractBigDecimalAssert<?> bigDecimalAssert) {
-      return Refaster.anyOf(
-          bigDecimalAssert.isNotZero(),
-          bigDecimalAssert.isNotEqualTo(0L),
-          bigDecimalAssert.isNotEqualTo(BigDecimal.ZERO));
-    }
-
-    @AfterTemplate
-    AbstractBigDecimalAssert<?> after(AbstractBigDecimalAssert<?> bigDecimalAssert) {
-      return bigDecimalAssert.isNotEqualTo(0);
-    }
-  }
-
-  static final class AbstractBigDecimalAssertIsOne {
-    @BeforeTemplate
-    AbstractBigDecimalAssert<?> before(AbstractBigDecimalAssert<?> bigDecimalAssert) {
-      return Refaster.anyOf(
-          bigDecimalAssert.isOne(),
-          bigDecimalAssert.isEqualTo(1L),
-          bigDecimalAssert.isEqualTo(BigDecimal.ONE));
-    }
-
-    @AfterTemplate
-    AbstractBigDecimalAssert<?> after(AbstractBigDecimalAssert<?> bigDecimalAssert) {
-      return bigDecimalAssert.isEqualTo(1);
+      return bigDecimalAssert.isNotEqualByComparingTo(n);
     }
   }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/AssertJBooleanTemplates.java

@@ -1,8 +1,8 @@
 package tech.picnic.errorprone.refastertemplates;
 
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
 import static org.assertj.core.api.Assertions.assertThat;
 
-import com.google.errorprone.refaster.ImportPolicy;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
@@ -59,7 +59,7 @@ final class AssertJBooleanTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     AbstractBooleanAssert<?> after(boolean b) {
       return assertThat(b).isTrue();
     }
@@ -88,7 +88,7 @@ final class AssertJBooleanTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     AbstractBooleanAssert<?> after(boolean b) {
       return assertThat(b).isFalse();
     }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/AssertJByteTemplates.java

@@ -15,11 +15,7 @@ final class AssertJByteTemplates {
     @BeforeTemplate
     AbstractByteAssert<?> before(AbstractByteAssert<?> byteAssert, byte n) {
       return Refaster.anyOf(
-          byteAssert.isCloseTo(n, offset((byte) 0)),
-          byteAssert.isCloseTo(Byte.valueOf(n), offset((byte) 0)),
-          byteAssert.isCloseTo(n, withPercentage(0)),
-          byteAssert.isCloseTo(Byte.valueOf(n), withPercentage(0)),
-          byteAssert.isEqualTo(Byte.valueOf(n)));
+          byteAssert.isCloseTo(n, offset((byte) 0)), byteAssert.isCloseTo(n, withPercentage(0)));
     }
 
     @AfterTemplate
@@ -33,10 +29,7 @@ final class AssertJByteTemplates {
     AbstractByteAssert<?> before(AbstractByteAssert<?> byteAssert, byte n) {
       return Refaster.anyOf(
           byteAssert.isNotCloseTo(n, offset((byte) 0)),
-          byteAssert.isNotCloseTo(Byte.valueOf(n), offset((byte) 0)),
-          byteAssert.isNotCloseTo(n, withPercentage(0)),
-          byteAssert.isNotCloseTo(Byte.valueOf(n), withPercentage(0)),
-          byteAssert.isNotEqualTo(Byte.valueOf(n)));
+          byteAssert.isNotCloseTo(n, withPercentage(0)));
     }
 
     @AfterTemplate

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/AssertJCharSequenceTemplates.java

@@ -1,8 +1,8 @@
 package tech.picnic.errorprone.refastertemplates;
 
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
 import static org.assertj.core.api.Assertions.assertThat;
 
-import com.google.errorprone.refaster.ImportPolicy;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
@@ -21,7 +21,7 @@ final class AssertJCharSequenceTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(CharSequence charSequence) {
       assertThat(charSequence).isEmpty();
     }
@@ -36,7 +36,7 @@ final class AssertJCharSequenceTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     AbstractAssert<?, ?> after(CharSequence charSequence) {
       return assertThat(charSequence).isNotEmpty();
     }
@@ -49,7 +49,7 @@ final class AssertJCharSequenceTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     AbstractAssert<?, ?> after(CharSequence charSequence, int length) {
       return assertThat(charSequence).hasSize(length);
     }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/AssertJDoubleTemplates.java

@@ -36,11 +36,7 @@ final class AssertJDoubleTemplates {
     @BeforeTemplate
     AbstractDoubleAssert<?> before(AbstractDoubleAssert<?> doubleAssert, double n) {
       return Refaster.anyOf(
-          doubleAssert.isCloseTo(n, offset(0.0)),
-          doubleAssert.isCloseTo(Double.valueOf(n), offset(0.0)),
-          doubleAssert.isCloseTo(n, withPercentage(0.0)),
-          doubleAssert.isCloseTo(Double.valueOf(n), withPercentage(0.0)),
-          doubleAssert.isEqualTo(Double.valueOf(n)));
+          doubleAssert.isCloseTo(n, offset(0.0)), doubleAssert.isCloseTo(n, withPercentage(0.0)));
     }
 
     @AfterTemplate
@@ -54,10 +50,7 @@ final class AssertJDoubleTemplates {
     AbstractDoubleAssert<?> before(AbstractDoubleAssert<?> doubleAssert, double n) {
       return Refaster.anyOf(
           doubleAssert.isNotCloseTo(n, offset(0.0)),
-          doubleAssert.isNotCloseTo(Double.valueOf(n), offset(0.0)),
-          doubleAssert.isNotCloseTo(n, withPercentage(0.0)),
-          doubleAssert.isNotCloseTo(Double.valueOf(n), withPercentage(0.0)),
-          doubleAssert.isNotEqualTo(Double.valueOf(n)));
+          doubleAssert.isNotCloseTo(n, withPercentage(0.0)));
     }
 
     @AfterTemplate

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/AssertJFloatTemplates.java

@@ -36,11 +36,7 @@ final class AssertJFloatTemplates {
     @BeforeTemplate
     AbstractFloatAssert<?> before(AbstractFloatAssert<?> floatAssert, float n) {
       return Refaster.anyOf(
-          floatAssert.isCloseTo(n, offset(0F)),
-          floatAssert.isCloseTo(Float.valueOf(n), offset(0F)),
-          floatAssert.isCloseTo(n, withPercentage(0)),
-          floatAssert.isCloseTo(Float.valueOf(n), withPercentage(0)),
-          floatAssert.isEqualTo(Float.valueOf(n)));
+          floatAssert.isCloseTo(n, offset(0F)), floatAssert.isCloseTo(n, withPercentage(0)));
     }
 
     @AfterTemplate
@@ -53,11 +49,7 @@ final class AssertJFloatTemplates {
     @BeforeTemplate
     AbstractFloatAssert<?> before(AbstractFloatAssert<?> floatAssert, float n) {
       return Refaster.anyOf(
-          floatAssert.isNotCloseTo(n, offset(0F)),
-          floatAssert.isNotCloseTo(Float.valueOf(n), offset(0F)),
-          floatAssert.isNotCloseTo(n, withPercentage(0)),
-          floatAssert.isNotCloseTo(Float.valueOf(n), withPercentage(0)),
-          floatAssert.isNotEqualTo(Float.valueOf(n)));
+          floatAssert.isNotCloseTo(n, offset(0F)), floatAssert.isNotCloseTo(n, withPercentage(0)));
     }
 
     @AfterTemplate

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/AssertJIntegerTemplates.java

@@ -15,11 +15,7 @@ final class AssertJIntegerTemplates {
     @BeforeTemplate
     AbstractIntegerAssert<?> before(AbstractIntegerAssert<?> intAssert, int n) {
       return Refaster.anyOf(
-          intAssert.isCloseTo(n, offset(0)),
-          intAssert.isCloseTo(Integer.valueOf(n), offset(0)),
-          intAssert.isCloseTo(n, withPercentage(0)),
-          intAssert.isCloseTo(Integer.valueOf(n), withPercentage(0)),
-          intAssert.isEqualTo(Integer.valueOf(n)));
+          intAssert.isCloseTo(n, offset(0)), intAssert.isCloseTo(n, withPercentage(0)));
     }
 
     @AfterTemplate
@@ -32,11 +28,7 @@ final class AssertJIntegerTemplates {
     @BeforeTemplate
     AbstractIntegerAssert<?> before(AbstractIntegerAssert<?> intAssert, int n) {
       return Refaster.anyOf(
-          intAssert.isNotCloseTo(n, offset(0)),
-          intAssert.isNotCloseTo(Integer.valueOf(n), offset(0)),
-          intAssert.isNotCloseTo(n, withPercentage(0)),
-          intAssert.isNotCloseTo(Integer.valueOf(n), withPercentage(0)),
-          intAssert.isNotEqualTo(Integer.valueOf(n)));
+          intAssert.isNotCloseTo(n, offset(0)), intAssert.isNotCloseTo(n, withPercentage(0)));
     }
 
     @AfterTemplate

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/AssertJLongTemplates.java

@@ -15,11 +15,7 @@ final class AssertJLongTemplates {
     @BeforeTemplate
     AbstractLongAssert<?> before(AbstractLongAssert<?> longAssert, long n) {
       return Refaster.anyOf(
-          longAssert.isCloseTo(n, offset(0L)),
-          longAssert.isCloseTo(Long.valueOf(n), offset(0L)),
-          longAssert.isCloseTo(n, withPercentage(0)),
-          longAssert.isCloseTo(Long.valueOf(n), withPercentage(0)),
-          longAssert.isEqualTo(Long.valueOf(n)));
+          longAssert.isCloseTo(n, offset(0L)), longAssert.isCloseTo(n, withPercentage(0)));
     }
 
     @AfterTemplate
@@ -32,11 +28,7 @@ final class AssertJLongTemplates {
     @BeforeTemplate
     AbstractLongAssert<?> before(AbstractLongAssert<?> longAssert, long n) {
       return Refaster.anyOf(
-          longAssert.isNotCloseTo(n, offset(0L)),
-          longAssert.isNotCloseTo(Long.valueOf(n), offset(0L)),
-          longAssert.isNotCloseTo(n, withPercentage(0)),
-          longAssert.isNotCloseTo(Long.valueOf(n), withPercentage(0)),
-          longAssert.isNotEqualTo(Long.valueOf(n)));
+          longAssert.isNotCloseTo(n, offset(0L)), longAssert.isNotCloseTo(n, withPercentage(0)));
     }
 
     @AfterTemplate

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/AssertJMapTemplates.java

@@ -0,0 +1,35 @@
+package tech.picnic.errorprone.refastertemplates;
+
+import com.google.common.collect.ImmutableMap;
+import com.google.errorprone.refaster.annotation.AfterTemplate;
+import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import java.util.Map;
+import org.assertj.core.api.AbstractMapAssert;
+
+final class AssertJMapTemplates {
+  private AssertJMapTemplates() {}
+
+  static final class AbstractMapAssertContainsExactlyInAnyOrderEntriesOf<K, V> {
+    @BeforeTemplate
+    AbstractMapAssert<?, ?, K, V> before(AbstractMapAssert<?, ?, K, V> mapAssert, Map<K, V> map) {
+      return mapAssert.isEqualTo(map);
+    }
+
+    @AfterTemplate
+    AbstractMapAssert<?, ?, K, V> after(AbstractMapAssert<?, ?, K, V> mapAssert, Map<K, V> map) {
+      return mapAssert.containsExactlyInAnyOrderEntriesOf(map);
+    }
+  }
+
+  static final class AbstractMapAssertContainsExactlyEntriesOf<K, V> {
+    @BeforeTemplate
+    AbstractMapAssert<?, ?, K, V> before(AbstractMapAssert<?, ?, K, V> mapAssert, K key, V value) {
+      return mapAssert.containsExactlyInAnyOrderEntriesOf(ImmutableMap.of(key, value));
+    }
+
+    @AfterTemplate
+    AbstractMapAssert<?, ?, K, V> after(AbstractMapAssert<?, ?, K, V> mapAssert, K key, V value) {
+      return mapAssert.containsExactlyEntriesOf(ImmutableMap.of(key, value));
+    }
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/AssertJNumberTemplates.java

@@ -1,8 +1,12 @@
 package tech.picnic.errorprone.refastertemplates;
 
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
+import static org.assertj.core.api.Assertions.assertThat;
+
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import com.google.errorprone.refaster.annotation.UseImportPolicy;
 import java.math.BigDecimal;
 import java.math.BigInteger;
 import org.assertj.core.api.AbstractBigDecimalAssert;
@@ -18,7 +22,7 @@ import org.assertj.core.api.NumberAssert;
 final class AssertJNumberTemplates {
   private AssertJNumberTemplates() {}
 
-  static final class NumberIsPositive {
+  static final class NumberAssertIsPositive {
     @BeforeTemplate
     AbstractByteAssert<?> before(AbstractByteAssert<?> numberAssert) {
       return Refaster.anyOf(
@@ -69,7 +73,7 @@ final class AssertJNumberTemplates {
     }
   }
 
-  static final class NumberIsNotPositive {
+  static final class NumberAssertIsNotPositive {
     @BeforeTemplate
     AbstractByteAssert<?> before(AbstractByteAssert<?> numberAssert) {
       return Refaster.anyOf(
@@ -120,7 +124,7 @@ final class AssertJNumberTemplates {
     }
   }
 
-  static final class NumberIsNegative {
+  static final class NumberAssertIsNegative {
     @BeforeTemplate
     AbstractByteAssert<?> before(AbstractByteAssert<?> numberAssert) {
       return Refaster.anyOf(
@@ -171,7 +175,7 @@ final class AssertJNumberTemplates {
     }
   }
 
-  static final class NumberIsNotNegative {
+  static final class NumberAssertIsNotNegative {
     @BeforeTemplate
     AbstractByteAssert<?> before(AbstractByteAssert<?> numberAssert) {
       return Refaster.anyOf(
@@ -221,4 +225,40 @@ final class AssertJNumberTemplates {
       return numberAssert.isNotNegative();
     }
   }
+
+  static final class AssertThatIsOdd {
+    @BeforeTemplate
+    AbstractIntegerAssert<?> before(int number) {
+      return assertThat(number % 2).isEqualTo(1);
+    }
+
+    @BeforeTemplate
+    AbstractLongAssert<?> before(long number) {
+      return assertThat(number % 2).isEqualTo(1);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    NumberAssert<?, ?> after(long number) {
+      return assertThat(number).isOdd();
+    }
+  }
+
+  static final class AssertThatIsEven {
+    @BeforeTemplate
+    AbstractIntegerAssert<?> before(int number) {
+      return assertThat(number % 2).isEqualTo(0);
+    }
+
+    @BeforeTemplate
+    AbstractLongAssert<?> before(long number) {
+      return assertThat(number % 2).isEqualTo(0);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    NumberAssert<?, ?> after(long number) {
+      return assertThat(number).isEven();
+    }
+  }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/AssertJObjectTemplates.java

@@ -1,13 +1,14 @@
 package tech.picnic.errorprone.refastertemplates;
 
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
 import static org.assertj.core.api.Assertions.assertThat;
 
-import com.google.errorprone.refaster.ImportPolicy;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import com.google.errorprone.refaster.annotation.UseImportPolicy;
 import org.assertj.core.api.AbstractBooleanAssert;
+import org.assertj.core.api.AbstractStringAssert;
 import org.assertj.core.api.ObjectAssert;
 
 final class AssertJObjectTemplates {
@@ -20,7 +21,7 @@ final class AssertJObjectTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ObjectAssert<S> after(S object) {
       return assertThat(object).isInstanceOf(Refaster.<T>clazz());
     }
@@ -33,7 +34,7 @@ final class AssertJObjectTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ObjectAssert<S> after(S object) {
       return assertThat(object).isNotInstanceOf(Refaster.<T>clazz());
     }
@@ -46,7 +47,7 @@ final class AssertJObjectTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ObjectAssert<S> after(S object1, T object2) {
       return assertThat(object1).isEqualTo(object2);
     }
@@ -59,9 +60,22 @@ final class AssertJObjectTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ObjectAssert<S> after(S object1, T object2) {
       return assertThat(object1).isNotEqualTo(object2);
     }
   }
+
+  static final class AssertThatHasToString<T> {
+    @BeforeTemplate
+    AbstractStringAssert<?> before(T object, String str) {
+      return assertThat(object.toString()).isEqualTo(str);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    ObjectAssert<T> after(T object, String str) {
+      return assertThat(object).hasToString(str);
+    }
+  }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/AssertJOptionalTemplates.java

@@ -1,8 +1,8 @@
 package tech.picnic.errorprone.refastertemplates;
 
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
 import static org.assertj.core.api.Assertions.assertThat;
 
-import com.google.errorprone.refaster.ImportPolicy;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
@@ -22,11 +22,11 @@ final class AssertJOptionalTemplates {
     @BeforeTemplate
     @SuppressWarnings("NullAway")
     ObjectAssert<T> before(Optional<T> optional) {
-      return assertThat(optional.get());
+      return assertThat(optional.orElseThrow());
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     AbstractObjectAssert<?, T> after(Optional<T> optional) {
       return assertThat(optional).get();
     }
@@ -53,7 +53,7 @@ final class AssertJOptionalTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     OptionalAssert<T> after(Optional<T> optional) {
       return assertThat(optional).isPresent();
     }
@@ -80,7 +80,7 @@ final class AssertJOptionalTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     OptionalAssert<T> after(Optional<T> optional) {
       return assertThat(optional).isEmpty();
     }
@@ -92,16 +92,29 @@ final class AssertJOptionalTemplates {
       return Refaster.anyOf(
           optionalAssert.get().isEqualTo(value),
           optionalAssert.isEqualTo(Optional.of(value)),
-          optionalAssert.contains(value));
+          optionalAssert.contains(value),
+          optionalAssert.isPresent().hasValue(value));
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
     AbstractOptionalAssert<?, T> after(AbstractOptionalAssert<?, T> optionalAssert, T value) {
       return optionalAssert.hasValue(value);
     }
   }
 
+  static final class AbstractOptionalAssertContainsSame<T> {
+    @BeforeTemplate
+    AbstractAssert<?, ?> before(AbstractOptionalAssert<?, T> optionalAssert, T value) {
+      return Refaster.anyOf(
+          optionalAssert.get().isSameAs(value), optionalAssert.isPresent().isSameAs(value));
+    }
+
+    @AfterTemplate
+    AbstractOptionalAssert<?, T> after(AbstractOptionalAssert<?, T> optionalAssert, T value) {
+      return optionalAssert.containsSame(value);
+    }
+  }
+
   static final class AssertThatOptionalHasValueMatching<T> {
     @BeforeTemplate
     AbstractOptionalAssert<?, T> before(Optional<T> optional, Predicate<? super T> predicate) {
@@ -109,7 +122,7 @@ final class AssertJOptionalTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     AbstractObjectAssert<?, T> after(Optional<T> optional, Predicate<? super T> predicate) {
       return assertThat(optional).get().matches(predicate);
     }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/AssertJShortTemplates.java

@@ -15,11 +15,7 @@ final class AssertJShortTemplates {
     @BeforeTemplate
     AbstractShortAssert<?> before(AbstractShortAssert<?> shortAssert, short n) {
       return Refaster.anyOf(
-          shortAssert.isCloseTo(n, offset((short) 0)),
-          shortAssert.isCloseTo(Short.valueOf(n), offset((short) 0)),
-          shortAssert.isCloseTo(n, withPercentage(0)),
-          shortAssert.isCloseTo(Short.valueOf(n), withPercentage(0)),
-          shortAssert.isEqualTo(Short.valueOf(n)));
+          shortAssert.isCloseTo(n, offset((short) 0)), shortAssert.isCloseTo(n, withPercentage(0)));
     }
 
     @AfterTemplate
@@ -33,10 +29,7 @@ final class AssertJShortTemplates {
     AbstractShortAssert<?> before(AbstractShortAssert<?> shortAssert, short n) {
       return Refaster.anyOf(
           shortAssert.isNotCloseTo(n, offset((short) 0)),
-          shortAssert.isNotCloseTo(Short.valueOf(n), offset((short) 0)),
-          shortAssert.isNotCloseTo(n, withPercentage(0)),
-          shortAssert.isNotCloseTo(Short.valueOf(n), withPercentage(0)),
-          shortAssert.isNotEqualTo(Short.valueOf(n)));
+          shortAssert.isNotCloseTo(n, withPercentage(0)));
     }
 
     @AfterTemplate

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/AssertJStringTemplates.java

@@ -1,8 +1,8 @@
 package tech.picnic.errorprone.refastertemplates;
 
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
 import static org.assertj.core.api.Assertions.assertThat;
 
-import com.google.errorprone.refaster.ImportPolicy;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import com.google.errorprone.refaster.annotation.UseImportPolicy;
@@ -31,7 +31,7 @@ final class AssertJStringTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(String string) {
       assertThat(string).isEmpty();
     }
@@ -56,9 +56,35 @@ final class AssertJStringTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     AbstractAssert<?, ?> after(String string) {
       return assertThat(string).isNotEmpty();
     }
   }
+
+  static final class AssertThatMatches {
+    @BeforeTemplate
+    AbstractAssert<?, ?> before(String string, String regex) {
+      return assertThat(string.matches(regex)).isTrue();
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractAssert<?, ?> after(String string, String regex) {
+      return assertThat(string).matches(regex);
+    }
+  }
+
+  static final class AssertThatDoesNotMatch {
+    @BeforeTemplate
+    AbstractAssert<?, ?> before(String string, String regex) {
+      return assertThat(string.matches(regex)).isFalse();
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractAssert<?, ?> after(String string, String regex) {
+      return assertThat(string).doesNotMatch(regex);
+    }
+  }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/AssertJTemplates.java

@@ -1,5 +1,6 @@
 package tech.picnic.errorprone.refastertemplates;
 
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
 import static org.assertj.core.api.Assertions.assertThat;
 
 import com.google.common.collect.ImmutableBiMap;
@@ -12,10 +13,10 @@ import com.google.common.collect.ImmutableSortedMultiset;
 import com.google.common.collect.ImmutableSortedSet;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Multiset;
-import com.google.errorprone.refaster.ImportPolicy;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import com.google.errorprone.refaster.annotation.NotMatches;
 import com.google.errorprone.refaster.annotation.Repeated;
 import com.google.errorprone.refaster.annotation.UseImportPolicy;
 import java.util.ArrayList;
@@ -38,6 +39,7 @@ import java.util.stream.Collector;
 import java.util.stream.Stream;
 import org.assertj.core.api.AbstractAssert;
 import org.assertj.core.api.AbstractBooleanAssert;
+import org.assertj.core.api.AbstractCollectionAssert;
 import org.assertj.core.api.AbstractComparableAssert;
 import org.assertj.core.api.AbstractDoubleAssert;
 import org.assertj.core.api.AbstractIntegerAssert;
@@ -51,6 +53,7 @@ import org.assertj.core.api.ObjectEnumerableAssert;
 import org.assertj.core.api.OptionalDoubleAssert;
 import org.assertj.core.api.OptionalIntAssert;
 import org.assertj.core.api.OptionalLongAssert;
+import tech.picnic.errorprone.refaster.util.IsArray;
 
 /** Refaster templates related to AssertJ expressions and statements. */
 // XXX: Most `AbstractIntegerAssert` rules can also be applied for other primitive types. Generate
@@ -94,13 +97,12 @@ import org.assertj.core.api.OptionalLongAssert;
 // XXX: Right now we use and import `Offset.offset` and `Percentage.withPercentage`. Use the AssertJ
 // methods instead. (Also in the TestNG migration.)
 //      ^ Also for `Tuple`!
-// XXX: Use `assertThatIllegalArgumentException` and variants.
 // XXX: `assertThatCode(x).isInstanceOf(clazz)` -> `assertThatThrownBy(x).isInstanceOf(clazz)`
 // (etc.)
 // XXX: Look into using Assertions#contentOf(URL url, Charset charset) instead of our own test
 // method.
 // XXX: Write Optional templates also for `OptionalInt` and variants.
-// XXX: Write plugin to flag `assertThat(compileTimeContant)` occurrences. Also other likely
+// XXX: Write plugin to flag `assertThat(compileTimeConstant)` occurrences. Also other likely
 // candidates, such as `assertThat(ImmutableSet(foo, bar)).XXX`
 // XXX: Write generic plugin to replace explicit array parameters with varargs (`new int[] {1, 2}`
 // -> `1, 2`).
@@ -113,6 +115,11 @@ import org.assertj.core.api.OptionalLongAssert;
 // somehow.
 // XXX: `abstractOptionalAssert.get().satisfies(pred)` ->
 // `abstractOptionalAssert.hasValueSatisfying(pred)`.
+// XXX: `assertThat(ImmutableList.sortedCopyOf(cmp, values)).somethingExactOrder` -> just compare
+// "in any order".
+// XXX: Turns out a lot of this is also covered by https://github.com/palantir/assertj-automation.
+// See how we can combine these things. Do note that (at present) their Refaster templates don't
+// show up as Error Prone checks. So we'd have to build an integration for that.
 final class AssertJTemplates {
   private AssertJTemplates() {}
 
@@ -129,7 +136,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     OptionalDoubleAssert after(OptionalDouble optional, double expected) {
       return assertThat(optional).hasValue(expected);
     }
@@ -148,7 +155,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     OptionalIntAssert after(OptionalInt optional, int expected) {
       return assertThat(optional).hasValue(expected);
     }
@@ -167,7 +174,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     OptionalLongAssert after(OptionalLong optional, long expected) {
       return assertThat(optional).hasValue(expected);
     }
@@ -333,8 +340,14 @@ final class AssertJTemplates {
                   ImmutableList.of(element),
                   Arrays.asList(element),
                   ImmutableSet.of(element),
-                  ImmutableMultiset.of(element))),
-          iterAssert.containsExactlyInAnyOrder(element));
+                  ImmutableMultiset.of(element))));
+    }
+
+    @BeforeTemplate
+    @SuppressWarnings("unchecked")
+    ObjectEnumerableAssert<?, S> before2(
+        ObjectEnumerableAssert<?, S> iterAssert, @NotMatches(IsArray.class) T element) {
+      return iterAssert.containsExactlyInAnyOrder(element);
     }
 
     @AfterTemplate
@@ -344,17 +357,28 @@ final class AssertJTemplates {
     }
   }
 
+  static final class AssertThatSetContainsExactlyOneElement<S, T extends S> {
+    @BeforeTemplate
+    ObjectEnumerableAssert<?, S> before(Set<S> set, T element) {
+      return assertThat(set).containsOnly(element);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    ObjectEnumerableAssert<?, S> after(Set<S> set, T element) {
+      return assertThat(set).containsExactly(element);
+    }
+  }
+
   static final class ObjectEnumerableContainsOneDistinctElement<S, T extends S> {
     @BeforeTemplate
-    @SuppressWarnings("unchecked")
     ObjectEnumerableAssert<?, S> before(ObjectEnumerableAssert<?, S> iterAssert, T element) {
-      return Refaster.anyOf(
-          iterAssert.hasSameElementsAs(
-              Refaster.anyOf(
-                  ImmutableList.of(element),
-                  Arrays.asList(element),
-                  ImmutableSet.of(element),
-                  ImmutableMultiset.of(element))));
+      return iterAssert.hasSameElementsAs(
+          Refaster.anyOf(
+              ImmutableList.of(element),
+              Arrays.asList(element),
+              ImmutableSet.of(element),
+              ImmutableMultiset.of(element)));
     }
 
     @AfterTemplate
@@ -366,15 +390,13 @@ final class AssertJTemplates {
 
   static final class ObjectEnumerableIsSubsetOfOneElement<S, T extends S> {
     @BeforeTemplate
-    @SuppressWarnings("unchecked")
     ObjectEnumerableAssert<?, S> before(ObjectEnumerableAssert<?, S> iterAssert, T element) {
-      return Refaster.anyOf(
-          iterAssert.isSubsetOf(
-              Refaster.anyOf(
-                  ImmutableList.of(element),
-                  Arrays.asList(element),
-                  ImmutableSet.of(element),
-                  ImmutableMultiset.of(element))));
+      return iterAssert.isSubsetOf(
+          Refaster.anyOf(
+              ImmutableList.of(element),
+              Arrays.asList(element),
+              ImmutableSet.of(element),
+              ImmutableMultiset.of(element)));
     }
 
     @AfterTemplate
@@ -392,8 +414,8 @@ final class AssertJTemplates {
     @BeforeTemplate
     void before(Iterable<E> iterable) {
       Refaster.anyOf(
+          assertThat(iterable).hasSize(0),
           assertThat(iterable.iterator().hasNext()).isFalse(),
-          assertThat(Iterables.size(iterable)).isEqualTo(0),
           assertThat(Iterables.size(iterable)).isEqualTo(0L),
           assertThat(Iterables.size(iterable)).isNotPositive());
     }
@@ -402,13 +424,12 @@ final class AssertJTemplates {
     void before(Collection<E> iterable) {
       Refaster.anyOf(
           assertThat(iterable.isEmpty()).isTrue(),
-          assertThat(iterable.size()).isEqualTo(0),
           assertThat(iterable.size()).isEqualTo(0L),
           assertThat(iterable.size()).isNotPositive());
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Collection<E> iterable) {
       assertThat(iterable).isEmpty();
     }
@@ -432,7 +453,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     IterableAssert<E> after(Iterable<E> iterable) {
       return assertThat(iterable).isNotEmpty();
     }
@@ -450,7 +471,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     IterableAssert<E> after(Iterable<E> iterable, int length) {
       return assertThat(iterable).hasSize(length);
     }
@@ -463,7 +484,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     IterableAssert<S> after(Iterable<S> iterable, T element) {
       return assertThat(iterable).containsExactly(element);
     }
@@ -480,7 +501,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     IterableAssert<S> after(Iterable<S> iterable, T element) {
       return assertThat(iterable).containsExactly(element);
     }
@@ -497,7 +518,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(List<S> list1, List<T> list2) {
       return assertThat(list1).containsExactlyElementsOf(list2);
     }
@@ -509,32 +530,32 @@ final class AssertJTemplates {
 
   static final class AssertThatSetsAreEqual<S, T extends S> {
     @BeforeTemplate
-    IterableAssert<S> before(Set<S> set1, Set<T> set2) {
+    AbstractCollectionAssert<?, ?, S, ?> before(Set<S> set1, Set<T> set2) {
       return Refaster.anyOf(
           assertThat(set1).isEqualTo(set2),
           assertThat(set1).containsExactlyInAnyOrderElementsOf(set2));
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
-    IterableAssert<S> after(Set<S> set1, Set<T> set2) {
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractCollectionAssert<?, ?, S, ?> after(Set<S> set1, Set<T> set2) {
       return assertThat(set1).hasSameElementsAs(set2);
     }
   }
 
   //
-  // Mutliset
+  // Multiset
   //
 
   static final class AssertThatMultisetsAreEqual<S, T extends S> {
     @BeforeTemplate
-    IterableAssert<S> before(Multiset<S> multiset1, Multiset<T> multiset2) {
+    AbstractCollectionAssert<?, ?, S, ?> before(Multiset<S> multiset1, Multiset<T> multiset2) {
       return assertThat(multiset1).isEqualTo(multiset2);
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
-    IterableAssert<S> after(Multiset<S> multiset1, Multiset<T> multiset2) {
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractCollectionAssert<?, ?, S, ?> after(Multiset<S> multiset1, Multiset<T> multiset2) {
       return assertThat(multiset1).containsExactlyInAnyOrderElementsOf(multiset2);
     }
   }
@@ -599,8 +620,8 @@ final class AssertJTemplates {
     @BeforeTemplate
     void before(Map<K, V> map) {
       Refaster.anyOf(
+          assertThat(map).hasSize(0),
           assertThat(map.isEmpty()).isTrue(),
-          assertThat(map.size()).isEqualTo(0),
           assertThat(map.size()).isEqualTo(0L),
           assertThat(map.size()).isNotPositive());
     }
@@ -611,7 +632,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Map<K, V> map) {
       assertThat(map).isEmpty();
     }
@@ -648,7 +669,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     MapAssert<K, V> after(Map<K, V> map) {
       return assertThat(map).isNotEmpty();
     }
@@ -663,7 +684,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     MapAssert<K, V> after(Map<K, V> map, int length) {
       return assertThat(map).hasSize(length);
     }
@@ -677,7 +698,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     MapAssert<K, V> after(Map<K, V> map1, Map<K, V> map2) {
       return assertThat(map1).hasSameSizeAs(map2);
     }
@@ -691,7 +712,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     MapAssert<K, V> after(Map<K, V> map, K key) {
       return assertThat(map).containsKey(key);
     }
@@ -704,7 +725,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     MapAssert<K, V> after(Map<K, V> map, K key) {
       return assertThat(map).doesNotContainKey(key);
     }
@@ -717,7 +738,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     MapAssert<K, V> after(Map<K, V> map, K key, V value) {
       return assertThat(map).containsEntry(key, value);
     }
@@ -742,7 +763,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, Iterable<U> iterable) {
       return assertThat(stream).containsAnyElementsOf(iterable);
     }
@@ -763,7 +784,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, U[] array) {
       return assertThat(stream).containsAnyOf(array);
     }
@@ -772,19 +793,22 @@ final class AssertJTemplates {
   // XXX: This rule assumes the `collector` doesn't completely discard certain values.
   static final class AssertThatStreamContainsAnyOfVarArgs<S, T extends S, U extends T> {
     @BeforeTemplate
+    @SuppressWarnings("AssertThatStreamContainsAnyOf" /* Varargs converted to array. */)
     IterableAssert<T> before(
         Stream<S> stream, Collector<S, ?, ? extends Iterable<T>> collector, @Repeated U elements) {
       return assertThat(stream.collect(collector)).containsAnyOf(Refaster.asVarargs(elements));
     }
 
     @BeforeTemplate
+    @SuppressWarnings("AssertThatStreamContainsAnyOf" /* Varargs converted to array. */)
     ListAssert<T> before2(
         Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, @Repeated U elements) {
       return assertThat(stream.collect(collector)).containsAnyOf(Refaster.asVarargs(elements));
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @SuppressWarnings("ObjectEnumerableContainsOneElement" /* Not a true singleton. */)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, @Repeated U elements) {
       return assertThat(stream).containsAnyOf(elements);
     }
@@ -805,7 +829,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, Iterable<U> iterable) {
       return assertThat(stream).containsAll(iterable);
     }
@@ -826,7 +850,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, U[] array) {
       return assertThat(stream).contains(array);
     }
@@ -835,19 +859,21 @@ final class AssertJTemplates {
   // XXX: This rule assumes the `collector` doesn't completely discard certain values.
   static final class AssertThatStreamContainsVarArgs<S, T extends S, U extends T> {
     @BeforeTemplate
+    @SuppressWarnings("AssertThatStreamContains" /* Varargs converted to array. */)
     IterableAssert<T> before(
         Stream<S> stream, Collector<S, ?, ? extends Iterable<T>> collector, @Repeated U elements) {
       return assertThat(stream.collect(collector)).contains(Refaster.asVarargs(elements));
     }
 
     @BeforeTemplate
+    @SuppressWarnings("AssertThatStreamContains" /* Varargs converted to array. */)
     ListAssert<T> before2(
         Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, @Repeated U elements) {
       return assertThat(stream.collect(collector)).contains(Refaster.asVarargs(elements));
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, @Repeated U elements) {
       return assertThat(stream).contains(elements);
     }
@@ -862,7 +888,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, Iterable<U> iterable) {
       return assertThat(stream).containsExactlyElementsOf(iterable);
     }
@@ -877,7 +903,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, U[] array) {
       return assertThat(stream).containsExactly(array);
     }
@@ -886,13 +912,14 @@ final class AssertJTemplates {
   // XXX: This rule assumes the `collector` doesn't completely discard certain values.
   static final class AssertThatStreamContainsExactlyVarargs<S, T extends S, U extends T> {
     @BeforeTemplate
+    @SuppressWarnings("AssertThatStreamContainsExactly" /* Varargs converted to array. */)
     ListAssert<T> before(
         Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, @Repeated U elements) {
       return assertThat(stream.collect(collector)).containsExactly(Refaster.asVarargs(elements));
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, @Repeated U elements) {
       return assertThat(stream).containsExactly(elements);
     }
@@ -908,13 +935,13 @@ final class AssertJTemplates {
     }
 
     @BeforeTemplate
-    IterableAssert<T> before2(
+    AbstractCollectionAssert<?, ?, T, ?> before2(
         Stream<S> stream, Collector<S, ?, ? extends Multiset<T>> collector, Iterable<U> iterable) {
       return assertThat(stream.collect(collector)).containsExactlyInAnyOrderElementsOf(iterable);
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, Iterable<U> iterable) {
       return assertThat(stream).containsExactlyInAnyOrderElementsOf(iterable);
     }
@@ -929,13 +956,13 @@ final class AssertJTemplates {
     }
 
     @BeforeTemplate
-    IterableAssert<T> before2(
+    AbstractCollectionAssert<?, ?, T, ?> before2(
         Stream<S> stream, Collector<S, ?, ? extends Multiset<T>> collector, U[] array) {
       return assertThat(stream.collect(collector)).containsExactlyInAnyOrder(array);
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, U[] array) {
       return assertThat(stream).containsExactlyInAnyOrder(array);
     }
@@ -944,6 +971,7 @@ final class AssertJTemplates {
   // XXX: This rule assumes the `collector` doesn't completely discard certain values.
   static final class AssertThatStreamContainsExactlyInAnyOrderVarArgs<S, T extends S, U extends T> {
     @BeforeTemplate
+    @SuppressWarnings("AssertThatStreamContainsExactlyInAnyOrder" /* Varargs converted to array. */)
     ListAssert<T> before(
         Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, @Repeated U elements) {
       return assertThat(stream.collect(collector))
@@ -951,14 +979,16 @@ final class AssertJTemplates {
     }
 
     @BeforeTemplate
-    IterableAssert<T> before2(
+    @SuppressWarnings("AssertThatStreamContainsExactlyInAnyOrder" /* Varargs converted to array. */)
+    AbstractCollectionAssert<?, ?, T, ?> before2(
         Stream<S> stream, Collector<S, ?, ? extends Multiset<T>> collector, @Repeated U elements) {
       return assertThat(stream.collect(collector))
           .containsExactlyInAnyOrder(Refaster.asVarargs(elements));
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @SuppressWarnings("ObjectEnumerableContainsExactlyOneElement" /* Not a true singleton. */)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, @Repeated U elements) {
       return assertThat(stream).containsExactlyInAnyOrder(elements);
     }
@@ -979,7 +1009,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, Iterable<U> iterable) {
       return assertThat(stream).containsSequence(iterable);
     }
@@ -988,13 +1018,15 @@ final class AssertJTemplates {
   // XXX: This rule assumes the `collector` doesn't completely discard certain values.
   static final class AssertThatStreamContainsSequenceVarArgs<S, T extends S, U extends T> {
     @BeforeTemplate
+    @SuppressWarnings("AssertThatStreamContainsSequence" /* Varargs converted to array. */)
     ListAssert<T> before(
         Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, @Repeated U elements) {
       return assertThat(stream.collect(collector)).containsSequence(Refaster.asVarargs(elements));
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @SuppressWarnings("ObjectEnumerableContainsOneElement" /* Not a true singleton. */)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, @Repeated U elements) {
       return assertThat(stream).containsSequence(elements);
     }
@@ -1015,7 +1047,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, Iterable<U> iterable) {
       return assertThat(stream).containsSubsequence(iterable);
     }
@@ -1024,6 +1056,7 @@ final class AssertJTemplates {
   // XXX: This rule assumes the `collector` doesn't completely discard certain values.
   static final class AssertThatStreamContainsSubsequenceVarArgs<S, T extends S, U extends T> {
     @BeforeTemplate
+    @SuppressWarnings("AssertThatStreamContainsSubsequence" /* Varargs converted to array. */)
     ListAssert<T> before(
         Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, @Repeated U elements) {
       return assertThat(stream.collect(collector))
@@ -1031,7 +1064,8 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @SuppressWarnings("ObjectEnumerableContainsOneElement" /* Not a true singleton. */)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, @Repeated U elements) {
       return assertThat(stream).containsSubsequence(elements);
     }
@@ -1052,7 +1086,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, Iterable<U> iterable) {
       return assertThat(stream).doesNotContainAnyElementsOf(iterable);
     }
@@ -1073,7 +1107,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, U[] array) {
       return assertThat(stream).doesNotContain(array);
     }
@@ -1082,19 +1116,21 @@ final class AssertJTemplates {
   // XXX: This rule assumes the `collector` doesn't completely discard certain values.
   static final class AssertThatStreamDoesNotContainVarArgs<S, T extends S, U extends T> {
     @BeforeTemplate
+    @SuppressWarnings("AssertThatStreamDoesNotContain" /* Varargs converted to array. */)
     IterableAssert<T> before(
         Stream<S> stream, Collector<S, ?, ? extends Iterable<T>> collector, @Repeated U elements) {
       return assertThat(stream.collect(collector)).doesNotContain(Refaster.asVarargs(elements));
     }
 
     @BeforeTemplate
+    @SuppressWarnings("AssertThatStreamDoesNotContain" /* Varargs converted to array. */)
     ListAssert<T> before2(
         Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, @Repeated U elements) {
       return assertThat(stream.collect(collector)).doesNotContain(Refaster.asVarargs(elements));
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, @Repeated U elements) {
       return assertThat(stream).doesNotContain(elements);
     }
@@ -1115,7 +1151,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, Iterable<U> iterable) {
       return assertThat(stream).doesNotContainSequence(iterable);
     }
@@ -1124,6 +1160,7 @@ final class AssertJTemplates {
   // XXX: This rule assumes the `collector` doesn't completely discard certain values.
   static final class AssertThatStreamDoesNotContainSequenceVarArgs<S, T extends S, U extends T> {
     @BeforeTemplate
+    @SuppressWarnings("AssertThatStreamDoesNotContainSequence" /* Varargs converted to array. */)
     ListAssert<T> before(
         Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, @Repeated U elements) {
       return assertThat(stream.collect(collector))
@@ -1131,7 +1168,8 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @SuppressWarnings("ObjectEnumerableDoesNotContainOneElement" /* Not a true singleton. */)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, @Repeated U elements) {
       return assertThat(stream).doesNotContainSequence(elements);
     }
@@ -1152,7 +1190,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, Iterable<U> iterable) {
       return assertThat(stream).hasSameElementsAs(iterable);
     }
@@ -1173,7 +1211,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, U[] array) {
       return assertThat(stream).containsOnly(array);
     }
@@ -1182,19 +1220,21 @@ final class AssertJTemplates {
   // XXX: This rule assumes the `collector` doesn't completely discard certain values.
   static final class AssertThatStreamContainsOnlyVarArgs<S, T extends S, U extends T> {
     @BeforeTemplate
+    @SuppressWarnings("AssertThatStreamContainsOnly" /* Varargs converted to array. */)
     IterableAssert<T> before(
         Stream<S> stream, Collector<S, ?, ? extends Iterable<T>> collector, @Repeated U elements) {
       return assertThat(stream.collect(collector)).containsOnly(Refaster.asVarargs(elements));
     }
 
     @BeforeTemplate
+    @SuppressWarnings("AssertThatStreamContainsOnly" /* Varargs converted to array. */)
     ListAssert<T> before2(
         Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, @Repeated U elements) {
       return assertThat(stream.collect(collector)).containsOnly(Refaster.asVarargs(elements));
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, @Repeated U elements) {
       return assertThat(stream).containsOnly(elements);
     }
@@ -1227,7 +1267,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, U[] iterable) {
       return assertThat(stream).isSubsetOf(iterable);
     }
@@ -1236,19 +1276,21 @@ final class AssertJTemplates {
   // XXX: This rule assumes the `collector` doesn't completely discard certain values.
   static final class AssertThatStreamIsSubsetOfVarArgs<S, T extends S, U extends T> {
     @BeforeTemplate
+    @SuppressWarnings("AssertThatStreamIsSubsetOf" /* Varargs converted to array. */)
     IterableAssert<T> before(
         Stream<S> stream, Collector<S, ?, ? extends Iterable<T>> collector, @Repeated U elements) {
       return assertThat(stream.collect(collector)).isSubsetOf(Refaster.asVarargs(elements));
     }
 
     @BeforeTemplate
+    @SuppressWarnings("AssertThatStreamIsSubsetOf" /* Varargs converted to array. */)
     ListAssert<T> before2(
         Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, @Repeated U elements) {
       return assertThat(stream.collect(collector)).isSubsetOf(Refaster.asVarargs(elements));
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ListAssert<S> after(Stream<S> stream, @Repeated U elements) {
       return assertThat(stream).isSubsetOf(elements);
     }
@@ -1267,7 +1309,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Stream<S> stream) {
       assertThat(stream).isEmpty();
     }
@@ -1286,7 +1328,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Stream<S> stream) {
       assertThat(stream).isNotEmpty();
     }
@@ -1299,7 +1341,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Stream<T> stream, int size) {
       assertThat(stream).hasSize(size);
     }
@@ -1316,7 +1358,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Predicate<T> predicate, T object) {
       assertThat(predicate).accepts(object);
     }
@@ -1329,7 +1371,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Predicate<T> predicate, T object) {
       assertThat(predicate).rejects(object);
     }
@@ -2170,7 +2212,7 @@ final class AssertJTemplates {
   //        }
   //
   //        @AfterTemplate
-  //        @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+  //        @UseImportPolicy(STATIC_IMPORT_ALWAYS)
   //        IterableAssert<E> after(Iterable<E> iterable, E expected) {
   //            return assertThat(iterable).containsExactly(expected);
   //        }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/AssertJThrowingCallableTemplates.java

@@ -0,0 +1,471 @@
+package tech.picnic.errorprone.refastertemplates;
+
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+import static org.assertj.core.api.Assertions.assertThatIOException;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
+import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
+import static org.assertj.core.api.Assertions.assertThatNullPointerException;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import com.google.errorprone.refaster.annotation.AfterTemplate;
+import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import com.google.errorprone.refaster.annotation.Repeated;
+import com.google.errorprone.refaster.annotation.UseImportPolicy;
+import java.io.IOException;
+import org.assertj.core.api.AbstractObjectAssert;
+import org.assertj.core.api.AbstractThrowableAssert;
+import org.assertj.core.api.ThrowableAssert.ThrowingCallable;
+
+/**
+ * Refaster templates related to AssertJ assertions over expressions that may throw a {@link
+ * Throwable} subtype.
+ *
+ * <p>For reasons of consistency we prefer {@link
+ * org.assertj.core.api.Assertions#assertThatThrownBy} over static methods for specific exception
+ * types. Note that only the most common assertion expressions are rewritten here; covering all
+ * cases would require the implementation of an Error Prone check instead.
+ */
+final class AssertJThrowingCallableTemplates {
+  private AssertJThrowingCallableTemplates() {}
+
+  static final class AssertThatThrownByIllegalArgumentException {
+    @BeforeTemplate
+    AbstractObjectAssert<?, ?> before(ThrowingCallable throwingCallable) {
+      return assertThatIllegalArgumentException().isThrownBy(throwingCallable);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(ThrowingCallable throwingCallable) {
+      return assertThatThrownBy(throwingCallable).isInstanceOf(IllegalArgumentException.class);
+    }
+  }
+
+  static final class AssertThatThrownByIllegalArgumentExceptionHasMessage {
+    @BeforeTemplate
+    @SuppressWarnings(
+        "AssertThatThrownByIllegalArgumentException" /* Matches strictly more specific expressions. */)
+    AbstractObjectAssert<?, ?> before(ThrowingCallable throwingCallable, String message) {
+      return assertThatIllegalArgumentException().isThrownBy(throwingCallable).withMessage(message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(ThrowingCallable throwingCallable, String message) {
+      return assertThatThrownBy(throwingCallable)
+          .isInstanceOf(IllegalArgumentException.class)
+          .hasMessage(message);
+    }
+  }
+
+  static final class AssertThatThrownByIllegalArgumentExceptionHasMessageParameters {
+    @BeforeTemplate
+    @SuppressWarnings(
+        "AssertThatThrownByIllegalArgumentException" /* Matches strictly more specific expressions. */)
+    AbstractObjectAssert<?, ?> before(
+        ThrowingCallable throwingCallable, String message, @Repeated Object parameters) {
+      return assertThatIllegalArgumentException()
+          .isThrownBy(throwingCallable)
+          .withMessage(message, parameters);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(
+        ThrowingCallable throwingCallable, String message, @Repeated Object parameters) {
+      return assertThatThrownBy(throwingCallable)
+          .isInstanceOf(IllegalArgumentException.class)
+          .hasMessage(message, parameters);
+    }
+  }
+
+  static final class AssertThatThrownByIllegalArgumentExceptionHasMessageStartingWith {
+    @BeforeTemplate
+    @SuppressWarnings(
+        "AssertThatThrownByIllegalArgumentException" /* Matches strictly more specific expressions. */)
+    AbstractObjectAssert<?, ?> before(ThrowingCallable throwingCallable, String message) {
+      return assertThatIllegalArgumentException()
+          .isThrownBy(throwingCallable)
+          .withMessageStartingWith(message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(ThrowingCallable throwingCallable, String message) {
+      return assertThatThrownBy(throwingCallable)
+          .isInstanceOf(IllegalArgumentException.class)
+          .hasMessageStartingWith(message);
+    }
+  }
+
+  static final class AssertThatThrownByIllegalArgumentExceptionHasMessageContaining {
+    @BeforeTemplate
+    @SuppressWarnings(
+        "AssertThatThrownByIllegalArgumentException" /* Matches strictly more specific expressions. */)
+    AbstractObjectAssert<?, ?> before(ThrowingCallable throwingCallable, String message) {
+      return assertThatIllegalArgumentException()
+          .isThrownBy(throwingCallable)
+          .withMessageContaining(message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(ThrowingCallable throwingCallable, String message) {
+      return assertThatThrownBy(throwingCallable)
+          .isInstanceOf(IllegalArgumentException.class)
+          .hasMessageContaining(message);
+    }
+  }
+
+  static final class AssertThatThrownByIllegalArgumentExceptionHasMessageNotContainingAny {
+    @BeforeTemplate
+    @SuppressWarnings(
+        "AssertThatThrownByIllegalArgumentException" /* Matches strictly more specific expressions. */)
+    AbstractObjectAssert<?, ?> before(
+        ThrowingCallable throwingCallable, @Repeated CharSequence values) {
+      return assertThatIllegalArgumentException()
+          .isThrownBy(throwingCallable)
+          .withMessageNotContainingAny(values);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(
+        ThrowingCallable throwingCallable, @Repeated CharSequence values) {
+      return assertThatThrownBy(throwingCallable)
+          .isInstanceOf(IllegalArgumentException.class)
+          .hasMessageNotContainingAny(values);
+    }
+  }
+
+  static final class AssertThatThrownByIllegalStateException {
+    @BeforeTemplate
+    AbstractObjectAssert<?, ?> before(ThrowingCallable throwingCallable) {
+      return assertThatIllegalStateException().isThrownBy(throwingCallable);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(ThrowingCallable throwingCallable) {
+      return assertThatThrownBy(throwingCallable).isInstanceOf(IllegalStateException.class);
+    }
+  }
+
+  static final class AssertThatThrownByIllegalStateExceptionHasMessage {
+    @BeforeTemplate
+    @SuppressWarnings(
+        "AssertThatThrownByIllegalStateException" /* Matches strictly more specific expressions. */)
+    AbstractObjectAssert<?, ?> before(ThrowingCallable throwingCallable, String message) {
+      return assertThatIllegalStateException().isThrownBy(throwingCallable).withMessage(message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(ThrowingCallable throwingCallable, String message) {
+      return assertThatThrownBy(throwingCallable)
+          .isInstanceOf(IllegalStateException.class)
+          .hasMessage(message);
+    }
+  }
+
+  static final class AssertThatThrownByIllegalStateExceptionHasMessageParameters {
+    @BeforeTemplate
+    @SuppressWarnings(
+        "AssertThatThrownByIllegalStateException" /* Matches strictly more specific expressions. */)
+    AbstractObjectAssert<?, ?> before(
+        ThrowingCallable throwingCallable, String message, @Repeated Object parameters) {
+      return assertThatIllegalStateException()
+          .isThrownBy(throwingCallable)
+          .withMessage(message, parameters);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(
+        ThrowingCallable throwingCallable, String message, @Repeated Object parameters) {
+      return assertThatThrownBy(throwingCallable)
+          .isInstanceOf(IllegalStateException.class)
+          .hasMessage(message, parameters);
+    }
+  }
+
+  static final class AssertThatThrownByIllegalStateExceptionHasMessageStartingWith {
+    @BeforeTemplate
+    @SuppressWarnings(
+        "AssertThatThrownByIllegalStateException" /* Matches strictly more specific expressions. */)
+    AbstractObjectAssert<?, ?> before(ThrowingCallable throwingCallable, String message) {
+      return assertThatIllegalStateException()
+          .isThrownBy(throwingCallable)
+          .withMessageStartingWith(message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(ThrowingCallable throwingCallable, String message) {
+      return assertThatThrownBy(throwingCallable)
+          .isInstanceOf(IllegalStateException.class)
+          .hasMessageStartingWith(message);
+    }
+  }
+
+  static final class AssertThatThrownByIllegalStateExceptionHasMessageContaining {
+    @BeforeTemplate
+    @SuppressWarnings(
+        "AssertThatThrownByIllegalStateException" /* Matches strictly more specific expressions. */)
+    AbstractObjectAssert<?, ?> before(ThrowingCallable throwingCallable, String message) {
+      return assertThatIllegalStateException()
+          .isThrownBy(throwingCallable)
+          .withMessageContaining(message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(ThrowingCallable throwingCallable, String message) {
+      return assertThatThrownBy(throwingCallable)
+          .isInstanceOf(IllegalStateException.class)
+          .hasMessageContaining(message);
+    }
+  }
+
+  static final class AssertThatThrownByIllegalStateExceptionHasMessageNotContaining {
+    @BeforeTemplate
+    @SuppressWarnings(
+        "AssertThatThrownByIllegalStateException" /* Matches strictly more specific expressions. */)
+    AbstractObjectAssert<?, ?> before(ThrowingCallable throwingCallable, String message) {
+      return assertThatIllegalStateException()
+          .isThrownBy(throwingCallable)
+          .withMessageNotContaining(message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(ThrowingCallable throwingCallable, String message) {
+      return assertThatThrownBy(throwingCallable)
+          .isInstanceOf(IllegalStateException.class)
+          .hasMessageNotContaining(message);
+    }
+  }
+
+  static final class AssertThatThrownByNullPointerException {
+    @BeforeTemplate
+    AbstractObjectAssert<?, ?> before(ThrowingCallable throwingCallable) {
+      return assertThatNullPointerException().isThrownBy(throwingCallable);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(ThrowingCallable throwingCallable) {
+      return assertThatThrownBy(throwingCallable).isInstanceOf(NullPointerException.class);
+    }
+  }
+
+  static final class AssertThatThrownByNullPointerExceptionHasMessage {
+    @BeforeTemplate
+    @SuppressWarnings(
+        "AssertThatThrownByNullPointerException" /* Matches strictly more specific expressions. */)
+    AbstractObjectAssert<?, ?> before(ThrowingCallable throwingCallable, String message) {
+      return assertThatNullPointerException().isThrownBy(throwingCallable).withMessage(message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(ThrowingCallable throwingCallable, String message) {
+      return assertThatThrownBy(throwingCallable)
+          .isInstanceOf(NullPointerException.class)
+          .hasMessage(message);
+    }
+  }
+
+  static final class AssertThatThrownByNullPointerExceptionHasMessageParameters {
+    @BeforeTemplate
+    @SuppressWarnings(
+        "AssertThatThrownByNullPointerException" /* Matches strictly more specific expressions. */)
+    AbstractObjectAssert<?, ?> before(
+        ThrowingCallable throwingCallable, String message, @Repeated Object parameters) {
+      return assertThatNullPointerException()
+          .isThrownBy(throwingCallable)
+          .withMessage(message, parameters);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(
+        ThrowingCallable throwingCallable, String message, @Repeated Object parameters) {
+      return assertThatThrownBy(throwingCallable)
+          .isInstanceOf(NullPointerException.class)
+          .hasMessage(message, parameters);
+    }
+  }
+
+  static final class AssertThatThrownByNullPointerExceptionHasMessageStartingWith {
+    @BeforeTemplate
+    @SuppressWarnings(
+        "AssertThatThrownByNullPointerException" /* Matches strictly more specific expressions. */)
+    AbstractObjectAssert<?, ?> before(ThrowingCallable throwingCallable, String message) {
+      return assertThatNullPointerException()
+          .isThrownBy(throwingCallable)
+          .withMessageStartingWith(message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(ThrowingCallable throwingCallable, String message) {
+      return assertThatThrownBy(throwingCallable)
+          .isInstanceOf(NullPointerException.class)
+          .hasMessageStartingWith(message);
+    }
+  }
+
+  static final class AssertThatThrownByIOException {
+    @BeforeTemplate
+    AbstractObjectAssert<?, ?> before(ThrowingCallable throwingCallable) {
+      return assertThatIOException().isThrownBy(throwingCallable);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(ThrowingCallable throwingCallable) {
+      return assertThatThrownBy(throwingCallable).isInstanceOf(IOException.class);
+    }
+  }
+
+  static final class AssertThatThrownByIOExceptionHasMessage {
+    @BeforeTemplate
+    @SuppressWarnings(
+        "AssertThatThrownByIOException" /* Matches strictly more specific expressions. */)
+    AbstractObjectAssert<?, ?> before(ThrowingCallable throwingCallable, String message) {
+      return assertThatIOException().isThrownBy(throwingCallable).withMessage(message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(ThrowingCallable throwingCallable, String message) {
+      return assertThatThrownBy(throwingCallable)
+          .isInstanceOf(IOException.class)
+          .hasMessage(message);
+    }
+  }
+
+  static final class AssertThatThrownByIOExceptionHasMessageParameters {
+    @BeforeTemplate
+    @SuppressWarnings(
+        "AssertThatThrownByIOException" /* Matches strictly more specific expressions. */)
+    AbstractObjectAssert<?, ?> before(
+        ThrowingCallable throwingCallable, String message, @Repeated Object parameters) {
+      return assertThatIOException().isThrownBy(throwingCallable).withMessage(message, parameters);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(
+        ThrowingCallable throwingCallable, String message, @Repeated Object parameters) {
+      return assertThatThrownBy(throwingCallable)
+          .isInstanceOf(IOException.class)
+          .hasMessage(message, parameters);
+    }
+  }
+
+  static final class AssertThatThrownBy {
+    @BeforeTemplate
+    AbstractObjectAssert<?, ?> before(
+        Class<? extends Throwable> exceptionType, ThrowingCallable throwingCallable) {
+      return assertThatExceptionOfType(exceptionType).isThrownBy(throwingCallable);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(
+        Class<? extends Throwable> exceptionType, ThrowingCallable throwingCallable) {
+      return assertThatThrownBy(throwingCallable).isInstanceOf(exceptionType);
+    }
+  }
+
+  static final class AssertThatThrownByHasMessage {
+    @BeforeTemplate
+    @SuppressWarnings("AssertThatThrownBy" /* Matches strictly more specific expressions. */)
+    AbstractObjectAssert<?, ?> before(
+        Class<? extends Throwable> exceptionType,
+        ThrowingCallable throwingCallable,
+        String message) {
+      return assertThatExceptionOfType(exceptionType)
+          .isThrownBy(throwingCallable)
+          .withMessage(message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(
+        Class<? extends Throwable> exceptionType,
+        ThrowingCallable throwingCallable,
+        String message) {
+      return assertThatThrownBy(throwingCallable).isInstanceOf(exceptionType).hasMessage(message);
+    }
+  }
+
+  static final class AssertThatThrownByHasMessageParameters {
+    @BeforeTemplate
+    @SuppressWarnings("AssertThatThrownBy" /* Matches strictly more specific expressions. */)
+    AbstractObjectAssert<?, ?> before(
+        Class<? extends Throwable> exceptionType,
+        ThrowingCallable throwingCallable,
+        String message,
+        @Repeated Object parameters) {
+      return assertThatExceptionOfType(exceptionType)
+          .isThrownBy(throwingCallable)
+          .withMessage(message, parameters);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(
+        Class<? extends Throwable> exceptionType,
+        ThrowingCallable throwingCallable,
+        String message,
+        @Repeated Object parameters) {
+      return assertThatThrownBy(throwingCallable)
+          .isInstanceOf(exceptionType)
+          .hasMessage(message, parameters);
+    }
+  }
+
+  // XXX: Drop this template in favour of a generic Error Prone check which flags
+  // `String.format(...)` arguments to a wide range of format methods.
+  static final class AbstractThrowableAssertHasMessage {
+    @BeforeTemplate
+    AbstractThrowableAssert<?, ? extends Throwable> before(
+        AbstractThrowableAssert<?, ? extends Throwable> abstractThrowableAssert,
+        String message,
+        @Repeated Object parameters) {
+      return abstractThrowableAssert.hasMessage(String.format(message, parameters));
+    }
+
+    @AfterTemplate
+    AbstractThrowableAssert<?, ? extends Throwable> after(
+        AbstractThrowableAssert<?, ? extends Throwable> abstractThrowableAssert,
+        String message,
+        @Repeated Object parameters) {
+      return abstractThrowableAssert.hasMessage(message, parameters);
+    }
+  }
+
+  // XXX: Drop this template in favour of a generic Error Prone check which flags
+  // `String.format(...)` arguments to a wide range of format methods.
+  static final class AbstractThrowableAssertWithFailMessage {
+    @BeforeTemplate
+    AbstractThrowableAssert<?, ? extends Throwable> before(
+        AbstractThrowableAssert<?, ? extends Throwable> abstractThrowableAssert,
+        String message,
+        @Repeated Object args) {
+      return abstractThrowableAssert.withFailMessage(String.format(message, args));
+    }
+
+    @AfterTemplate
+    AbstractThrowableAssert<?, ? extends Throwable> after(
+        AbstractThrowableAssert<?, ? extends Throwable> abstractThrowableAssert,
+        String message,
+        @Repeated Object args) {
+      return abstractThrowableAssert.withFailMessage(message, args);
+    }
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/AssortedTemplates.java

@@ -1,15 +1,18 @@
 package tech.picnic.errorprone.refastertemplates;
 
+import static com.google.common.base.Preconditions.checkElementIndex;
 import static com.google.common.collect.ImmutableSet.toImmutableSet;
+import static com.google.common.collect.Sets.toImmutableEnumSet;
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
+import static java.util.Collections.disjoint;
+import static java.util.Objects.checkIndex;
 
-import com.google.common.base.Preconditions;
 import com.google.common.base.Splitter;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Iterators;
 import com.google.common.collect.Sets;
 import com.google.common.collect.Streams;
-import com.google.errorprone.refaster.ImportPolicy;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
@@ -18,6 +21,7 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.EnumMap;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Objects;
@@ -36,12 +40,12 @@ final class AssortedTemplates {
   static final class CheckIndex {
     @BeforeTemplate
     int before(int index, int size) {
-      return Preconditions.checkElementIndex(index, size);
+      return checkElementIndex(index, size);
     }
 
     @AfterTemplate
     int after(int index, int size) {
-      return Objects.checkIndex(index, size);
+      return checkIndex(index, size);
     }
   }
 
@@ -60,14 +64,14 @@ final class AssortedTemplates {
   }
 
   static final class MapGetOrNull<K, V, L> {
-    @Nullable
     @BeforeTemplate
+    @Nullable
     V before(Map<K, V> map, L key) {
       return map.getOrDefault(key, null);
     }
 
-    @Nullable
     @AfterTemplate
+    @Nullable
     V after(Map<K, V> map, L key) {
       return map.get(key);
     }
@@ -81,6 +85,7 @@ final class AssortedTemplates {
    * original code produces a set which iterates over the elements in encounter order, the
    * replacement code iterates over the elements in enum definition order.
    */
+  // XXX: ^ Consider emitting a comment warning about this fact?
   static final class StreamToImmutableEnumSet<T extends Enum<T>> {
     @BeforeTemplate
     ImmutableSet<T> before(Stream<T> stream) {
@@ -88,9 +93,9 @@ final class AssortedTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ImmutableSet<T> after(Stream<T> stream) {
-      return stream.collect(Sets.toImmutableEnumSet());
+      return stream.collect(toImmutableEnumSet());
     }
   }
 
@@ -104,15 +109,15 @@ final class AssortedTemplates {
           Streams.stream(iterator).findAny().orElse(defaultValue));
     }
 
-    @Nullable
     @AfterTemplate
+    @Nullable
     T after(Iterator<T> iterator, T defaultValue) {
       return Iterators.getNext(iterator, defaultValue);
     }
   }
 
   /** Don't unnecessarily repeat boolean expressions. */
-  // XXX: This template only captures only the simplest case. `@AlsoNegation` doesn't help. Consider
+  // XXX: This template captures only the simplest case. `@AlsoNegation` doesn't help. Consider
   // contributing a Refaster patch which handles the negation in the `@BeforeTemplate` more
   // intelligently.
   static final class LogicalImplication {
@@ -158,20 +163,43 @@ final class AssortedTemplates {
 
     @AfterTemplate
     boolean after(Set<T> set1, Set<T> set2) {
-      return Collections.disjoint(set1, set2);
+      return disjoint(set1, set2);
     }
   }
 
-  /** Avoid {@link Iterables#isEmpty(Iterable)}; the JDK alternative is just as well. */
+  /**
+   * Don't unnecessarily copy collections before passing them to {@link
+   * Collections#disjoint(Collection, Collection)}.
+   */
+  // XXX: Other copy operations could be elided too, but these are most common after application of
+  // the `DisjointSets` template defined above. If we ever introduce a generic "makes a copy"
+  // stand-in, use it here.
+  static final class DisjointCollections<T> {
+    @BeforeTemplate
+    boolean before(Collection<T> collection1, Collection<T> collection2) {
+      return Refaster.anyOf(
+          disjoint(ImmutableSet.copyOf(collection1), collection2),
+          disjoint(new HashSet<>(collection1), collection2),
+          disjoint(collection1, ImmutableSet.copyOf(collection2)),
+          disjoint(collection1, new HashSet<>(collection2)));
+    }
+
+    @AfterTemplate
+    boolean after(Collection<T> collection1, Collection<T> collection2) {
+      return disjoint(collection1, collection2);
+    }
+  }
+
+  /** Prefer {@link Iterables#isEmpty(Iterable)} over more contrived alternatives. */
   static final class IterableIsEmpty<T> {
     @BeforeTemplate
     boolean before(Iterable<T> iterable) {
-      return Iterables.isEmpty(iterable);
+      return !iterable.iterator().hasNext();
     }
 
     @AfterTemplate
     boolean after(Iterable<T> iterable) {
-      return iterable.iterator().hasNext();
+      return Iterables.isEmpty(iterable);
     }
   }
 
@@ -230,11 +258,6 @@ final class AssortedTemplates {
   //
   //   @BeforeTemplate
   //   void before(Supplier<T> supplier) {
-  //     anyStatement(supplier::get);
-  //   }
-  //
-  //   @BeforeTemplate
-  //   void before2(Supplier<T> supplier) {
   //     anyStatement(() -> supplier.get());
   //   }
   //

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/CollectionTemplates.java

@@ -10,22 +10,39 @@ import com.google.errorprone.refaster.annotation.AlsoNegation;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Iterator;
 import java.util.List;
 import java.util.NavigableSet;
 import java.util.Optional;
 import java.util.Queue;
+import java.util.Set;
 import java.util.SortedSet;
+import java.util.function.IntFunction;
 import java.util.stream.Stream;
 
 /** Refaster templates related to expressions dealing with (arbitrary) collections. */
+// XXX: There are other Guava `Iterables` methods that should not be called if the input is known to
+// be a `Collection`. Add those here.
 final class CollectionTemplates {
   private CollectionTemplates() {}
 
-  /** Prefer {@link Collection#isEmpty()} over alternatives that consult the collection's size. */
+  /**
+   * Prefer {@link Collection#isEmpty()} over alternatives that consult the collection's size or are
+   * otherwise more contrived.
+   */
   static final class CollectionIsEmpty<T> {
     @BeforeTemplate
     boolean before(Collection<T> collection) {
-      return Refaster.anyOf(collection.size() == 0, collection.size() <= 0, collection.size() < 1);
+      return Refaster.anyOf(
+          collection.size() == 0,
+          collection.size() <= 0,
+          collection.size() < 1,
+          Iterables.isEmpty(collection));
+    }
+
+    @BeforeTemplate
+    boolean before(ImmutableCollection<T> collection) {
+      return collection.asList().isEmpty();
     }
 
     @AfterTemplate
@@ -35,6 +52,24 @@ final class CollectionTemplates {
     }
   }
 
+  /** Prefer {@link Collection#size()} over more contrived alternatives. */
+  static final class CollectionSize<T> {
+    @BeforeTemplate
+    int before(Collection<T> collection) {
+      return Iterables.size(collection);
+    }
+
+    @BeforeTemplate
+    int before(ImmutableCollection<T> collection) {
+      return collection.asList().size();
+    }
+
+    @AfterTemplate
+    int after(Collection<T> collection) {
+      return collection.size();
+    }
+  }
+
   /**
    * Don't call {@link Iterables#addAll(Collection, Iterable)} when the elements to be added are
    * already part of a {@link Collection}.
@@ -95,31 +130,32 @@ final class CollectionTemplates {
     }
   }
 
-  static final class CollectionRemoveAllFromCollectionBlock<T, S extends T> {
+  static final class SetRemoveAllCollection<T, S extends T> {
     @BeforeTemplate
-    void before(Collection<T> removeTo, Collection<S> elementsToRemove) {
-      elementsToRemove.forEach(removeTo::remove);
+    void before(Set<T> removeFrom, Collection<S> elementsToRemove) {
+      elementsToRemove.forEach(removeFrom::remove);
     }
 
     @BeforeTemplate
-    void before2(Collection<T> removeTo, Collection<S> elementsToRemove) {
+    void before2(Set<T> removeFrom, Collection<S> elementsToRemove) {
       for (T element : elementsToRemove) {
-        removeTo.remove(element);
+        removeFrom.remove(element);
       }
     }
 
     // XXX: This method is identical to `before2` except for the loop type. Make Refaster smarter so
-    // that this is supported out of the box.
+    // that this is supported out of the box. After doing so, also drop the `S extends T` type
+    // constraint; ideally this check applies to any `S`.
     @BeforeTemplate
-    void before3(Collection<T> removeTo, Collection<S> elementsToRemove) {
+    void before3(Set<T> removeFrom, Collection<S> elementsToRemove) {
       for (S element : elementsToRemove) {
-        removeTo.remove(element);
+        removeFrom.remove(element);
       }
     }
 
     @AfterTemplate
-    void after(Collection<T> removeTo, Collection<S> elementsToRemove) {
-      removeTo.removeAll(elementsToRemove);
+    void after(Set<T> removeFrom, Collection<S> elementsToRemove) {
+      removeFrom.removeAll(elementsToRemove);
     }
   }
 
@@ -153,17 +189,7 @@ final class CollectionTemplates {
    * Don't call {@link ImmutableCollection#asList()} if the result is going to be streamed; stream
    * directly.
    */
-  // XXX: Similar rules could be implemented for the following variants:
-  // collection.asList().contains(null);
-  // collection.asList().isEmpty();
-  // collection.asList().iterator();
-  // collection.asList().parallelStream();
-  // collection.asList().size();
-  // collection.asList().toArray();
-  // collection.asList().toArray(Object[]::new);
-  // collection.asList().toArray(new Object[0]);
-  // collection.asList().toString();
-  static final class ImmutableCollectionAsListToStream<T> {
+  static final class ImmutableCollectionStream<T> {
     @BeforeTemplate
     Stream<T> before(ImmutableCollection<T> collection) {
       return collection.asList().stream();
@@ -175,6 +201,121 @@ final class CollectionTemplates {
     }
   }
 
+  /**
+   * Don't call {@link ImmutableCollection#asList()} if {@link Collection#contains(Object)} is
+   * called on the result; call it directly.
+   */
+  static final class ImmutableCollectionContains<T, S> {
+    @BeforeTemplate
+    boolean before(ImmutableCollection<T> collection, S elem) {
+      return collection.asList().contains(elem);
+    }
+
+    @AfterTemplate
+    boolean after(ImmutableCollection<T> collection, S elem) {
+      return collection.contains(elem);
+    }
+  }
+
+  /**
+   * Don't call {@link ImmutableCollection#asList()} if {@link ImmutableCollection#parallelStream()}
+   * is called on the result; call it directly.
+   */
+  static final class ImmutableCollectionParallelStream<T> {
+    @BeforeTemplate
+    Stream<T> before(ImmutableCollection<T> collection) {
+      return collection.asList().parallelStream();
+    }
+
+    @AfterTemplate
+    Stream<T> after(ImmutableCollection<T> collection) {
+      return collection.parallelStream();
+    }
+  }
+
+  /**
+   * Don't call {@link ImmutableCollection#asList()} if {@link ImmutableCollection#toString()} is
+   * called on the result; call it directly.
+   */
+  static final class ImmutableCollectionToString<T> {
+    @BeforeTemplate
+    String before(ImmutableCollection<T> collection) {
+      return collection.asList().toString();
+    }
+
+    @AfterTemplate
+    String after(ImmutableCollection<T> collection) {
+      return collection.toString();
+    }
+  }
+
+  /** Prefer calling {@link Collection#toArray()} over more contrived alternatives. */
+  static final class CollectionToArray<T> {
+    @BeforeTemplate
+    Object[] before(Collection<T> collection, int size) {
+      return Refaster.anyOf(
+          collection.toArray(new Object[size]), collection.toArray(Object[]::new));
+    }
+
+    @BeforeTemplate
+    Object[] before(ImmutableCollection<T> collection) {
+      return collection.asList().toArray();
+    }
+
+    @AfterTemplate
+    Object[] after(Collection<T> collection) {
+      return collection.toArray();
+    }
+  }
+
+  /**
+   * Don't call {@link ImmutableCollection#asList()} if {@link
+   * ImmutableCollection#toArray(Object[])}` is called on the result; call it directly.
+   */
+  static final class ImmutableCollectionToArrayWithArray<T, S> {
+    @BeforeTemplate
+    Object[] before(ImmutableCollection<T> collection, S[] array) {
+      return collection.asList().toArray(array);
+    }
+
+    @AfterTemplate
+    Object[] after(ImmutableCollection<T> collection, S[] array) {
+      return collection.toArray(array);
+    }
+  }
+
+  /**
+   * Don't call {@link ImmutableCollection#asList()} if {@link
+   * ImmutableCollection#toArray(IntFunction)}} is called on the result; call it directly.
+   */
+  static final class ImmutableCollectionToArrayWithGenerator<T, S> {
+    @BeforeTemplate
+    S[] before(ImmutableCollection<T> collection, IntFunction<S[]> generator) {
+      return collection.asList().toArray(generator);
+    }
+
+    @AfterTemplate
+    S[] after(ImmutableCollection<T> collection, IntFunction<S[]> generator) {
+      return collection.toArray(generator);
+    }
+  }
+
+  /**
+   * Don't call {@link ImmutableCollection#asList()} if {@link ImmutableCollection#iterator()} is
+   * called on the result; call it directly.
+   */
+  static final class ImmutableCollectionIterator<T> {
+    @BeforeTemplate
+    Iterator<T> before(ImmutableCollection<T> collection) {
+      return collection.asList().iterator();
+    }
+
+    @AfterTemplate
+    Iterator<T> after(ImmutableCollection<T> collection) {
+      return collection.iterator();
+    }
+  }
+
   /**
    * Don't use the ternary operator to extract the first element of a possibly-empty {@link
    * Collection} as an {@link Optional}.

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/ComparatorTemplates.java

@@ -1,49 +1,46 @@
 package tech.picnic.errorprone.refastertemplates;
 
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
+import static java.util.Comparator.comparing;
+import static java.util.Comparator.comparingDouble;
+import static java.util.Comparator.comparingInt;
+import static java.util.Comparator.comparingLong;
+import static java.util.Comparator.naturalOrder;
+import static java.util.Comparator.reverseOrder;
 import static java.util.function.Function.identity;
 
-import com.google.errorprone.refaster.ImportPolicy;
+import com.google.common.collect.Comparators;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import com.google.errorprone.refaster.annotation.UseImportPolicy;
+import java.util.Arrays;
+import java.util.Collections;
 import java.util.Comparator;
 import java.util.function.Function;
+import java.util.function.ToDoubleFunction;
+import java.util.function.ToIntFunction;
+import java.util.function.ToLongFunction;
 
 /** Refaster templates related to expressions dealing with {@link Comparator}s. */
 final class ComparatorTemplates {
   private ComparatorTemplates() {}
 
   /** Prefer {@link Comparator#naturalOrder()} over more complicated constructs. */
-  static final class NaturalOrderComparator<T extends Comparable<? super T>> {
+  static final class NaturalOrder<T extends Comparable<? super T>> {
     // XXX: Drop the `Refaster.anyOf` if/when we decide to rewrite one to the other.
     @BeforeTemplate
     Comparator<T> before() {
-      return Refaster.anyOf(Comparator.comparing(Refaster.anyOf(identity(), v -> v)));
+      return Refaster.anyOf(
+          comparing(Refaster.anyOf(identity(), v -> v)), Comparator.<T>reverseOrder().reversed());
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     Comparator<T> after() {
-      return Comparator.naturalOrder();
-    }
-  }
-
-  /**
-   * Where applicable, prefer {@link Comparator#naturalOrder()} over {@link Function#identity()}, as
-   * it more clearly states intent.
-   */
-  static final class NaturalOrderComparatorFallback<T extends Comparable<? super T>> {
-    // XXX: Drop the `Refaster.anyOf` if/when we decide to rewrite one to the other.
-    @BeforeTemplate
-    Comparator<T> before(Comparator<T> cmp) {
-      return cmp.thenComparing(Refaster.anyOf(identity(), v -> v));
-    }
-
-    @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
-    Comparator<T> after(Comparator<T> cmp) {
-      return cmp.thenComparing(Comparator.naturalOrder());
+      return naturalOrder();
     }
   }
 
@@ -55,9 +52,211 @@ final class ComparatorTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     Comparator<T> after() {
-      return Comparator.reverseOrder();
+      return reverseOrder();
+    }
+  }
+
+  static final class CustomComparator<T> {
+    // XXX: Drop the `Refaster.anyOf` if/when we decide to rewrite one to the other.
+    @BeforeTemplate
+    Comparator<T> before(Comparator<T> cmp) {
+      return comparing(Refaster.anyOf(identity(), v -> v), cmp);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    Comparator<T> after(Comparator<T> cmp) {
+      return cmp;
+    }
+  }
+
+  /** Don't explicitly create {@link Comparator}s unnecessarily. */
+  static final class ThenComparing<S, T extends Comparable<? super T>> {
+    @BeforeTemplate
+    Comparator<S> before(Comparator<S> cmp, Function<? super S, ? extends T> function) {
+      return cmp.thenComparing(comparing(function));
+    }
+
+    @AfterTemplate
+    Comparator<S> after(Comparator<S> cmp, Function<? super S, ? extends T> function) {
+      return cmp.thenComparing(function);
+    }
+  }
+
+  /** Don't explicitly create {@link Comparator}s unnecessarily. */
+  static final class ThenComparingReversed<S, T extends Comparable<? super T>> {
+    @BeforeTemplate
+    Comparator<S> before(Comparator<S> cmp, Function<? super S, ? extends T> function) {
+      return cmp.thenComparing(comparing(function).reversed());
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    Comparator<S> after(Comparator<S> cmp, Function<? super S, ? extends T> function) {
+      return cmp.thenComparing(function, reverseOrder());
+    }
+  }
+
+  /** Don't explicitly create {@link Comparator}s unnecessarily. */
+  static final class ThenComparingCustom<S, T> {
+    @BeforeTemplate
+    Comparator<S> before(
+        Comparator<S> cmp, Function<? super S, ? extends T> function, Comparator<? super T> cmp2) {
+      return cmp.thenComparing(comparing(function, cmp2));
+    }
+
+    @AfterTemplate
+    Comparator<S> after(
+        Comparator<S> cmp, Function<? super S, ? extends T> function, Comparator<? super T> cmp2) {
+      return cmp.thenComparing(function, cmp2);
+    }
+  }
+
+  /** Don't explicitly create {@link Comparator}s unnecessarily. */
+  static final class ThenComparingCustomReversed<S, T> {
+    @BeforeTemplate
+    Comparator<S> before(
+        Comparator<S> cmp, Function<? super S, ? extends T> function, Comparator<? super T> cmp2) {
+      return cmp.thenComparing(comparing(function, cmp2).reversed());
+    }
+
+    @AfterTemplate
+    Comparator<S> after(
+        Comparator<S> cmp, Function<? super S, ? extends T> function, Comparator<? super T> cmp2) {
+      return cmp.thenComparing(function, cmp2.reversed());
+    }
+  }
+
+  /** Don't explicitly create {@link Comparator}s unnecessarily. */
+  static final class ThenComparingDouble<T> {
+    @BeforeTemplate
+    Comparator<T> before(Comparator<T> cmp, ToDoubleFunction<? super T> function) {
+      return cmp.thenComparing(comparingDouble(function));
+    }
+
+    @AfterTemplate
+    Comparator<T> after(Comparator<T> cmp, ToDoubleFunction<? super T> function) {
+      return cmp.thenComparingDouble(function);
+    }
+  }
+
+  /** Don't explicitly create {@link Comparator}s unnecessarily. */
+  static final class ThenComparingInt<T> {
+    @BeforeTemplate
+    Comparator<T> before(Comparator<T> cmp, ToIntFunction<? super T> function) {
+      return cmp.thenComparing(comparingInt(function));
+    }
+
+    @AfterTemplate
+    Comparator<T> after(Comparator<T> cmp, ToIntFunction<? super T> function) {
+      return cmp.thenComparingInt(function);
+    }
+  }
+
+  /** Don't explicitly create {@link Comparator}s unnecessarily. */
+  static final class ThenComparingLong<T> {
+    @BeforeTemplate
+    Comparator<T> before(Comparator<T> cmp, ToLongFunction<? super T> function) {
+      return cmp.thenComparing(comparingLong(function));
+    }
+
+    @AfterTemplate
+    Comparator<T> after(Comparator<T> cmp, ToLongFunction<? super T> function) {
+      return cmp.thenComparingLong(function);
+    }
+  }
+
+  /**
+   * Where applicable, prefer {@link Comparator#naturalOrder()} over {@link Function#identity()}, as
+   * it more clearly states intent.
+   */
+  static final class ThenComparingNaturalOrder<T extends Comparable<? super T>> {
+    // XXX: Drop the `Refaster.anyOf` if/when we decide to rewrite one to the other.
+    @BeforeTemplate
+    Comparator<T> before(Comparator<T> cmp) {
+      return cmp.thenComparing(Refaster.anyOf(identity(), v -> v));
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    Comparator<T> after(Comparator<T> cmp) {
+      return cmp.thenComparing(naturalOrder());
+    }
+  }
+
+  /** Prefer {@link Comparators#min(Comparable, Comparable)}} over more verbose alternatives. */
+  static final class MinOfPairNaturalOrder<T extends Comparable<? super T>> {
+    @BeforeTemplate
+    T before(T value1, T value2) {
+      return Collections.min(
+          Refaster.anyOf(
+              Arrays.asList(value1, value2),
+              ImmutableList.of(value1, value2),
+              ImmutableSet.of(value1, value2)));
+    }
+
+    @AfterTemplate
+    T after(T value1, T value2) {
+      return Comparators.min(value1, value2);
+    }
+  }
+
+  /**
+   * Prefer {@link Comparators#min(Object, Object, Comparator)}}} over more verbose alternatives.
+   */
+  static final class MinOfPairCustomOrder<T> {
+    @BeforeTemplate
+    T before(T value1, T value2, Comparator<T> cmp) {
+      return Collections.min(
+          Refaster.anyOf(
+              Arrays.asList(value1, value2),
+              ImmutableList.of(value1, value2),
+              ImmutableSet.of(value1, value2)),
+          cmp);
+    }
+
+    @AfterTemplate
+    T after(T value1, T value2, Comparator<T> cmp) {
+      return Comparators.min(value1, value2, cmp);
+    }
+  }
+
+  /** Prefer {@link Comparators#max(Comparable, Comparable)}} over more verbose alternatives. */
+  static final class MaxOfPairNaturalOrder<T extends Comparable<? super T>> {
+    @BeforeTemplate
+    T before(T value1, T value2) {
+      return Collections.max(
+          Refaster.anyOf(
+              Arrays.asList(value1, value2),
+              ImmutableList.of(value1, value2),
+              ImmutableSet.of(value1, value2)));
+    }
+
+    @AfterTemplate
+    T after(T value1, T value2) {
+      return Comparators.max(value1, value2);
+    }
+  }
+
+  /**
+   * Prefer {@link Comparators#max(Object, Object, Comparator)}}} over more verbose alternatives.
+   */
+  static final class MaxOfPairCustomOrder<T> {
+    @BeforeTemplate
+    T before(T value1, T value2, Comparator<T> cmp) {
+      return Collections.max(
+          Refaster.anyOf(
+              Arrays.asList(value1, value2),
+              ImmutableList.of(value1, value2),
+              ImmutableSet.of(value1, value2)),
+          cmp);
+    }
+
+    @AfterTemplate
+    T after(T value1, T value2, Comparator<T> cmp) {
+      return Comparators.max(value1, value2, cmp);
     }
   }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/DoubleStreamTemplates.java

@@ -6,6 +6,7 @@ import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import com.google.errorprone.refaster.annotation.MayOptionallyUse;
 import com.google.errorprone.refaster.annotation.Placeholder;
+import java.util.OptionalDouble;
 import java.util.function.DoubleFunction;
 import java.util.function.DoublePredicate;
 import java.util.function.DoubleUnaryOperator;
@@ -172,6 +173,18 @@ final class DoubleStreamTemplates {
     }
   }
 
+  static final class DoubleStreamMin {
+    @BeforeTemplate
+    OptionalDouble before(DoubleStream stream) {
+      return stream.sorted().findFirst();
+    }
+
+    @AfterTemplate
+    OptionalDouble after(DoubleStream stream) {
+      return stream.min();
+    }
+  }
+
   /** Prefer {@link DoubleStream#noneMatch(DoublePredicate)} over more contrived alternatives. */
   static final class DoubleStreamNoneMatch {
     @BeforeTemplate
@@ -220,10 +233,7 @@ final class DoubleStreamTemplates {
   static final class DoubleStreamAllMatch {
     @BeforeTemplate
     boolean before(DoubleStream stream, DoublePredicate predicate) {
-      return Refaster.anyOf(
-          stream.noneMatch(predicate.negate()),
-          !stream.anyMatch(predicate.negate()),
-          stream.filter(predicate.negate()).findAny().isEmpty());
+      return stream.noneMatch(predicate.negate());
     }
 
     @AfterTemplate
@@ -238,10 +248,7 @@ final class DoubleStreamTemplates {
 
     @BeforeTemplate
     boolean before(DoubleStream stream) {
-      return Refaster.anyOf(
-          stream.noneMatch(e -> !test(e)),
-          !stream.anyMatch(e -> !test(e)),
-          stream.filter(e -> !test(e)).findAny().isEmpty());
+      return stream.noneMatch(e -> !test(e));
     }
 
     @AfterTemplate

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/EqualityTemplates.java

@@ -4,7 +4,6 @@ import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.AlsoNegation;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
-import com.google.errorprone.refaster.annotation.NoAutoboxing;
 import java.util.Objects;
 import java.util.function.Predicate;
 
@@ -12,49 +11,31 @@ import java.util.function.Predicate;
 final class EqualityTemplates {
   private EqualityTemplates() {}
 
-  /** Prefer primitive/reference-based quality for primitives and enums. */
-  static final class PrimitiveOrReferenceEquality {
-    @NoAutoboxing
-    @BeforeTemplate
-    boolean before(boolean a, boolean b) {
-      return Objects.equals(a, b);
-    }
-
-    @NoAutoboxing
-    @BeforeTemplate
-    boolean before(long a, long b) {
-      return Objects.equals(a, b);
-    }
-
-    @NoAutoboxing
-    @BeforeTemplate
-    boolean before(double a, double b) {
-      return Objects.equals(a, b);
-    }
-
+  /** Prefer reference-based quality for enums. */
+  // Primitive value comparisons are not listed, because Error Prone flags those out of the box.
+  static final class PrimitiveOrReferenceEquality<T extends Enum<T>> {
     /**
      * Enums can be compared by reference. It is safe to do so even in the face of refactorings,
      * because if the type is ever converted to a non-enum, then Error-Prone will complain about any
      * remaining reference-based equality checks.
      */
     // XXX: This Refaster rule is the topic of https://github.com/google/error-prone/issues/559. We
-    // work around the issue by selecting the "largest replacements". See RefasterCheck.
+    // work around the issue by selecting the "largest replacements". See the `Refaster` check.
     @BeforeTemplate
-    <T extends Enum<T>> boolean before(T a, T b) {
+    boolean before(T a, T b) {
       return Refaster.anyOf(a.equals(b), Objects.equals(a, b));
     }
 
-    @AlsoNegation
     @AfterTemplate
-    boolean after(boolean a, boolean b) {
+    @AlsoNegation
+    boolean after(T a, T b) {
       return a == b;
     }
   }
 
   /** Prefer {@link Object#equals(Object)} over the equivalent lambda function. */
-  // XXX: As it stands, this rule is a special case of what `MethodReferenceUsageCheck` tries to
-  // achieve. If/when `MethodReferenceUsageCheck` becomes production ready, we should simply drop
-  // this check.
+  // XXX: As it stands, this rule is a special case of what `MethodReferenceUsage` tries to achieve.
+  // If/when `MethodReferenceUsage` becomes production ready, we should simply drop this check.
   // XXX: Alternatively, the rule should be replaced with a plugin which also identifies cases where
   // the arguments are swapped but simplification is possible anyway, by virtue of `v` being
   // non-null.

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/ImmutableListMultimapTemplates.java

@@ -2,6 +2,7 @@ package tech.picnic.errorprone.refastertemplates;
 
 import static com.google.common.collect.ImmutableListMultimap.flatteningToImmutableListMultimap;
 import static com.google.common.collect.ImmutableListMultimap.toImmutableListMultimap;
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
 import static java.util.function.Function.identity;
 
 import com.google.common.collect.ImmutableListMultimap;
@@ -12,7 +13,6 @@ import com.google.common.collect.Multimaps;
 import com.google.common.collect.SetMultimap;
 import com.google.common.collect.SortedSetMultimap;
 import com.google.common.collect.Streams;
-import com.google.errorprone.refaster.ImportPolicy;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
@@ -56,10 +56,7 @@ final class ImmutableListMultimapTemplates {
   static final class EmptyImmutableListMultimap<K, V> {
     @BeforeTemplate
     ImmutableMultimap<K, V> before() {
-      return Refaster.anyOf(
-          ImmutableListMultimap.<K, V>builder().build(),
-          ImmutableMultimap.<K, V>builder().build(),
-          ImmutableMultimap.of());
+      return Refaster.anyOf(ImmutableListMultimap.<K, V>builder().build(), ImmutableMultimap.of());
     }
 
     @AfterTemplate
@@ -80,7 +77,6 @@ final class ImmutableListMultimapTemplates {
     ImmutableMultimap<K, V> before(K key, V value) {
       return Refaster.anyOf(
           ImmutableListMultimap.<K, V>builder().put(key, value).build(),
-          ImmutableMultimap.<K, V>builder().put(key, value).build(),
           ImmutableMultimap.of(key, value));
     }
 
@@ -96,12 +92,11 @@ final class ImmutableListMultimapTemplates {
    */
   static final class EntryToImmutableListMultimap<K, V> {
     @BeforeTemplate
-    ImmutableMultimap<K, V> before(Map.Entry<? extends K, ? extends V> entry) {
+    ImmutableListMultimap<K, V> before(Map.Entry<? extends K, ? extends V> entry) {
       return Refaster.anyOf(
           ImmutableListMultimap.<K, V>builder().put(entry).build(),
-          Stream.of(entry).collect(toImmutableListMultimap(Map.Entry::getKey, Map.Entry::getValue)),
-          ImmutableMultimap.<K, V>builder().put(entry).build(),
-          ImmutableMultimap.of(entry.getKey(), entry.getValue()));
+          Stream.of(entry)
+              .collect(toImmutableListMultimap(Map.Entry::getKey, Map.Entry::getValue)));
     }
 
     @AfterTemplate
@@ -118,8 +113,7 @@ final class ImmutableListMultimapTemplates {
           ImmutableListMultimap.copyOf(iterable.entries()),
           ImmutableListMultimap.<K, V>builder().putAll(iterable).build(),
           ImmutableMultimap.copyOf(iterable),
-          ImmutableMultimap.copyOf(iterable.entries()),
-          ImmutableMultimap.<K, V>builder().putAll(iterable).build());
+          ImmutableMultimap.copyOf(iterable.entries()));
     }
 
     @BeforeTemplate
@@ -129,7 +123,6 @@ final class ImmutableListMultimapTemplates {
           ImmutableListMultimap.<K, V>builder().putAll(iterable).build(),
           Streams.stream(iterable)
               .collect(toImmutableListMultimap(Map.Entry::getKey, Map.Entry::getValue)),
-          ImmutableMultimap.<K, V>builder().putAll(iterable).build(),
           ImmutableMultimap.copyOf(iterable));
     }
 
@@ -168,7 +161,7 @@ final class ImmutableListMultimapTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ImmutableListMultimap<K, V> after(Stream<E> stream) {
       return stream.collect(toImmutableListMultimap(e -> keyFunction(e), e -> valueFunction(e)));
     }
@@ -279,17 +272,4 @@ final class ImmutableListMultimapTemplates {
       return ImmutableListMultimap.copyOf(Multimaps.transformValues(multimap, transformation));
     }
   }
-
-  /** Don't unnecessarily copy an {@link ImmutableListMultimap}. */
-  static final class ImmutableListMultimapCopyOfImmutableListMultimap<K, V> {
-    @BeforeTemplate
-    ImmutableListMultimap<K, V> before(ImmutableListMultimap<K, V> multimap) {
-      return ImmutableListMultimap.copyOf(multimap);
-    }
-
-    @AfterTemplate
-    ImmutableListMultimap<K, V> after(ImmutableListMultimap<K, V> multimap) {
-      return multimap;
-    }
-  }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/ImmutableListTemplates.java

@@ -2,21 +2,20 @@ package tech.picnic.errorprone.refastertemplates;
 
 import static com.google.common.collect.ImmutableList.toImmutableList;
 import static com.google.common.collect.ImmutableSet.toImmutableSet;
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
+import static java.util.Collections.emptyList;
+import static java.util.Collections.singletonList;
 import static java.util.Comparator.naturalOrder;
-import static java.util.stream.Collectors.collectingAndThen;
-import static java.util.stream.Collectors.toList;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Streams;
-import com.google.errorprone.refaster.ImportPolicy;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import com.google.errorprone.refaster.annotation.UseImportPolicy;
 import java.util.Arrays;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.Comparator;
 import java.util.Iterator;
 import java.util.List;
@@ -41,48 +40,15 @@ final class ImmutableListTemplates {
     }
   }
 
-  /** Prefer {@link ImmutableList#of()} over more contrived alternatives. */
-  static final class EmptyImmutableList<T> {
-    @BeforeTemplate
-    ImmutableList<T> before() {
-      return Refaster.anyOf(
-          ImmutableList.<T>builder().build(), Stream.<T>empty().collect(toImmutableList()));
-    }
-
-    @AfterTemplate
-    ImmutableList<T> after() {
-      return ImmutableList.of();
-    }
-  }
-
-  /**
-   * Prefer {@link ImmutableList#of(Object)} over alternatives that don't communicate the
-   * immutability of the resulting list at the type level.
-   */
-  // XXX: Note that this rewrite rule is incorrect for nullable elements.
-  static final class SingletonImmutableList<T> {
-    @BeforeTemplate
-    List<T> before(T element) {
-      return Collections.singletonList(element);
-    }
-
-    @AfterTemplate
-    ImmutableList<T> after(T element) {
-      return ImmutableList.of(element);
-    }
-  }
-
   /**
    * Prefer {@link ImmutableList#copyOf(Iterable)} and variants over more contrived alternatives.
    */
   static final class IterableToImmutableList<T> {
-    // XXX: Drop the inner `Refaster.anyOf` if/when we introduce a rule to choose between one and
-    // the other.
     @BeforeTemplate
     ImmutableList<T> before(T[] iterable) {
       return Refaster.anyOf(
           ImmutableList.<T>builder().add(iterable).build(),
-          Refaster.anyOf(Stream.of(iterable), Arrays.stream(iterable)).collect(toImmutableList()));
+          Arrays.stream(iterable).collect(toImmutableList()));
     }
 
     @BeforeTemplate
@@ -110,40 +76,20 @@ final class ImmutableListTemplates {
     }
   }
 
-  /** Prefer {@link ImmutableList#toImmutableList()} over the more verbose alternative. */
-  // XXX: Once the code base has been sufficiently cleaned up, we might want to also rewrite
-  // `Collectors.toList(`), with the caveat that it allows mutation (though this cannot be relied
-  // upon) as well as nulls. Another option is to explicitly rewrite those variants to
-  // `Collectors.toSet(ArrayList::new)`.
+  /** Prefer {@link ImmutableList#toImmutableList()} over less idiomatic alternatives. */
   static final class StreamToImmutableList<T> {
     @BeforeTemplate
     ImmutableList<T> before(Stream<T> stream) {
-      return Refaster.anyOf(
-          ImmutableList.copyOf(stream.iterator()),
-          ImmutableList.copyOf(stream::iterator),
-          stream.collect(collectingAndThen(toList(), ImmutableList::copyOf)));
+      return ImmutableList.copyOf(stream.iterator());
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ImmutableList<T> after(Stream<T> stream) {
       return stream.collect(toImmutableList());
     }
   }
 
-  /** Don't call {@link ImmutableList#asList()}; it is a no-op. */
-  static final class ImmutableListAsList<T> {
-    @BeforeTemplate
-    ImmutableList<T> before(ImmutableList<T> list) {
-      return list.asList();
-    }
-
-    @AfterTemplate
-    ImmutableList<T> after(ImmutableList<T> list) {
-      return list;
-    }
-  }
-
   /** Prefer {@link ImmutableList#sortedCopyOf(Iterable)} over more contrived alternatives. */
   static final class ImmutableListSortedCopyOf<T extends Comparable<? super T>> {
     @BeforeTemplate
@@ -197,9 +143,122 @@ final class ImmutableListTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ImmutableList<T> after(Stream<T> stream) {
       return stream.collect(toImmutableSet()).asList();
     }
   }
+
+  /**
+   * Prefer {@link ImmutableList#of()} over more contrived alternatives or alternatives that don't
+   * communicate the immutability of the resulting list at the type level.
+   */
+  // XXX: The `Stream` variant may be too contrived to warrant inclusion. Review its usage if/when
+  // this and similar Refaster templates are replaced with an Error Prone check.
+  static final class ImmutableListOf<T> {
+    @BeforeTemplate
+    List<T> before() {
+      return Refaster.anyOf(
+          ImmutableList.<T>builder().build(),
+          Stream.<T>empty().collect(toImmutableList()),
+          emptyList(),
+          List.of());
+    }
+
+    @AfterTemplate
+    ImmutableList<T> after() {
+      return ImmutableList.of();
+    }
+  }
+
+  /**
+   * Prefer {@link ImmutableList#of(Object)} over more contrived alternatives or alternatives that
+   * don't communicate the immutability of the resulting list at the type level.
+   */
+  // XXX: Note that the replacement of `Collections#singletonList` is incorrect for nullable
+  // elements.
+  static final class ImmutableListOf1<T> {
+    @BeforeTemplate
+    List<T> before(T e1) {
+      return Refaster.anyOf(
+          ImmutableList.<T>builder().add(e1).build(), singletonList(e1), List.of(e1));
+    }
+
+    @AfterTemplate
+    ImmutableList<T> after(T e1) {
+      return ImmutableList.of(e1);
+    }
+  }
+
+  /**
+   * Prefer {@link ImmutableList#of(Object, Object)} over alternatives that don't communicate the
+   * immutability of the resulting list at the type level.
+   */
+  // XXX: Consider writing an Error Prone check which also flags straightforward
+  // `ImmutableList.builder()` usages.
+  static final class ImmutableListOf2<T> {
+    @BeforeTemplate
+    List<T> before(T e1, T e2) {
+      return List.of(e1, e2);
+    }
+
+    @AfterTemplate
+    ImmutableList<T> after(T e1, T e2) {
+      return ImmutableList.of(e1, e2);
+    }
+  }
+
+  /**
+   * Prefer {@link ImmutableList#of(Object, Object, Object)} over alternatives that don't
+   * communicate the immutability of the resulting list at the type level.
+   */
+  // XXX: Consider writing an Error Prone check which also flags straightforward
+  // `ImmutableList.builder()` usages.
+  static final class ImmutableListOf3<T> {
+    @BeforeTemplate
+    List<T> before(T e1, T e2, T e3) {
+      return List.of(e1, e2, e3);
+    }
+
+    @AfterTemplate
+    ImmutableList<T> after(T e1, T e2, T e3) {
+      return ImmutableList.of(e1, e2, e3);
+    }
+  }
+
+  /**
+   * Prefer {@link ImmutableList#of(Object, Object, Object, Object)} over alternatives that don't
+   * communicate the immutability of the resulting list at the type level.
+   */
+  // XXX: Consider writing an Error Prone check which also flags straightforward
+  // `ImmutableList.builder()` usages.
+  static final class ImmutableListOf4<T> {
+    @BeforeTemplate
+    List<T> before(T e1, T e2, T e3, T e4) {
+      return List.of(e1, e2, e3, e4);
+    }
+
+    @AfterTemplate
+    ImmutableList<T> after(T e1, T e2, T e3, T e4) {
+      return ImmutableList.of(e1, e2, e3, e4);
+    }
+  }
+
+  /**
+   * Prefer {@link ImmutableList#of(Object, Object, Object, Object, Object)} over alternatives that
+   * don't communicate the immutability of the resulting list at the type level.
+   */
+  // XXX: Consider writing an Error Prone check which also flags straightforward
+  // `ImmutableList.builder()` usages.
+  static final class ImmutableListOf5<T> {
+    @BeforeTemplate
+    List<T> before(T e1, T e2, T e3, T e4, T e5) {
+      return List.of(e1, e2, e3, e4, e5);
+    }
+
+    @AfterTemplate
+    ImmutableList<T> after(T e1, T e2, T e3, T e4, T e5) {
+      return ImmutableList.of(e1, e2, e3, e4, e5);
+    }
+  }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/ImmutableMapTemplates.java

@@ -1,12 +1,14 @@
 package tech.picnic.errorprone.refastertemplates;
 
 import static com.google.common.collect.ImmutableMap.toImmutableMap;
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
+import static java.util.Collections.emptyMap;
+import static java.util.Collections.singletonMap;
 import static java.util.function.Function.identity;
 
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Maps;
 import com.google.common.collect.Streams;
-import com.google.errorprone.refaster.ImportPolicy;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
@@ -14,7 +16,6 @@ import com.google.errorprone.refaster.annotation.MayOptionallyUse;
 import com.google.errorprone.refaster.annotation.Placeholder;
 import com.google.errorprone.refaster.annotation.UseImportPolicy;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Set;
@@ -40,41 +41,6 @@ final class ImmutableMapTemplates {
     }
   }
 
-  /** Prefer {@link ImmutableMap#of()} over more contrived alternatives. */
-  static final class EmptyImmutableMap<K, V> {
-    @BeforeTemplate
-    ImmutableMap<K, V> before() {
-      return ImmutableMap.<K, V>builder().build();
-    }
-
-    @AfterTemplate
-    ImmutableMap<K, V> after() {
-      return ImmutableMap.of();
-    }
-  }
-
-  /**
-   * Prefer {@link ImmutableMap#of(Object, Object)} over more contrived alternatives and
-   * alternatives that don't communicate the immutability of the resulting map at the type level..
-   */
-  // XXX: One can define variants for more than one key-value pair, but at some point the builder
-  // actually produces nicer code. So it's not clear we should add Refaster templates for those
-  // variants.
-  // XXX: Note that the `singletonMap` rewrite rule is incorrect for nullable elements.
-  static final class PairToImmutableMap<K, V> {
-    @BeforeTemplate
-    Map<K, V> before(K key, V value) {
-      return Refaster.anyOf(
-          ImmutableMap.<K, V>builder().put(key, value).build(),
-          Collections.singletonMap(key, value));
-    }
-
-    @AfterTemplate
-    ImmutableMap<K, V> after(K key, V value) {
-      return ImmutableMap.of(key, value);
-    }
-  }
-
   /** Prefer {@link ImmutableMap#of(Object, Object)} over more contrived alternatives. */
   static final class EntryToImmutableMap<K, V> {
     @BeforeTemplate
@@ -178,7 +144,7 @@ final class ImmutableMapTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ImmutableMap<K, V> after(Stream<E> stream) {
       return stream.collect(toImmutableMap(e -> keyFunction(e), e -> valueFunction(e)));
     }
@@ -226,7 +192,7 @@ final class ImmutableMapTemplates {
 
     // XXX: Instead of `Map.Entry::getKey` we could also match `e -> e.getKey()`. But for some
     // reason Refaster doesn't handle that case. This doesn't matter if we roll out use of
-    // `MethodReferenceUsageCheck`. Same observation applies to a lot of other Refaster checks.
+    // `MethodReferenceUsage`. Same observation applies to a lot of other Refaster checks.
     @BeforeTemplate
     @SuppressWarnings("NullAway")
     ImmutableMap<K, V2> before(Map<K, V1> map) {
@@ -242,16 +208,108 @@ final class ImmutableMapTemplates {
     }
   }
 
-  /** Don't unnecessarily copy an {@link ImmutableMap}. */
-  static final class ImmutableMapCopyOfImmutableMap<K, V> {
+  /**
+   * Prefer {@link ImmutableMap#of()} over more contrived alternatives or alternatives that don't
+   * communicate the immutability of the resulting map at the type level.
+   */
+  static final class ImmutableMapOf<K, V> {
     @BeforeTemplate
-    ImmutableMap<K, V> before(ImmutableMap<K, V> map) {
-      return ImmutableMap.copyOf(map);
+    Map<K, V> before() {
+      return Refaster.anyOf(ImmutableMap.<K, V>builder().build(), emptyMap(), Map.of());
     }
 
     @AfterTemplate
-    ImmutableMap<K, V> after(ImmutableMap<K, V> map) {
-      return map;
+    ImmutableMap<K, V> after() {
+      return ImmutableMap.of();
+    }
+  }
+
+  /**
+   * Prefer {@link ImmutableMap#of(Object, Object)} over more contrived alternatives or alternatives
+   * that don't communicate the immutability of the resulting map at the type level.
+   */
+  // XXX: Note that the replacement of `Collections#singletonMap` is incorrect for nullable
+  // elements.
+  static final class ImmutableMapOf1<K, V> {
+    @BeforeTemplate
+    Map<K, V> before(K k1, V v1) {
+      return Refaster.anyOf(
+          ImmutableMap.<K, V>builder().put(k1, v1).build(), singletonMap(k1, v1), Map.of(k1, v1));
+    }
+
+    @AfterTemplate
+    ImmutableMap<K, V> after(K k1, V v1) {
+      return ImmutableMap.of(k1, v1);
+    }
+  }
+
+  /**
+   * Prefer {@link ImmutableMap#of(Object, Object, Object, Object)} over alternatives that don't
+   * communicate the immutability of the resulting map at the type level.
+   */
+  // XXX: Also rewrite the `ImmutableMap.builder()` variant?
+  static final class ImmutableMapOf2<K, V> {
+    @BeforeTemplate
+    Map<K, V> before(K k1, V v1, K k2, V v2) {
+      return Map.of(k1, v1, k2, v2);
+    }
+
+    @AfterTemplate
+    ImmutableMap<K, V> after(K k1, V v1, K k2, V v2) {
+      return ImmutableMap.of(k1, v1, k2, v2);
+    }
+  }
+
+  /**
+   * Prefer {@link ImmutableMap#of(Object, Object, Object, Object, Object, Object)} over
+   * alternatives that don't communicate the immutability of the resulting map at the type level.
+   */
+  // XXX: Also rewrite the `ImmutableMap.builder()` variant?
+  static final class ImmutableMapOf3<K, V> {
+    @BeforeTemplate
+    Map<K, V> before(K k1, V v1, K k2, V v2, K k3, V v3) {
+      return Map.of(k1, v1, k2, v2, k3, v3);
+    }
+
+    @AfterTemplate
+    ImmutableMap<K, V> after(K k1, V v1, K k2, V v2, K k3, V v3) {
+      return ImmutableMap.of(k1, v1, k2, v2, k3, v3);
+    }
+  }
+
+  /**
+   * Prefer {@link ImmutableMap#of(Object, Object, Object, Object, Object, Object, Object, Object)}
+   * over alternatives that don't communicate the immutability of the resulting map at the type
+   * level.
+   */
+  // XXX: Also rewrite the `ImmutableMap.builder()` variant?
+  static final class ImmutableMapOf4<K, V> {
+    @BeforeTemplate
+    Map<K, V> before(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {
+      return Map.of(k1, v1, k2, v2, k3, v3, k4, v4);
+    }
+
+    @AfterTemplate
+    ImmutableMap<K, V> after(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {
+      return ImmutableMap.of(k1, v1, k2, v2, k3, v3, k4, v4);
+    }
+  }
+
+  /**
+   * Prefer {@link ImmutableMap#of(Object, Object, Object, Object, Object, Object, Object, Object,
+   * Object, Object)} over alternatives that don't communicate the immutability of the resulting map
+   * at the type level.
+   */
+  // XXX: Also rewrite the `ImmutableMap.builder()` variant?
+  static final class ImmutableMapOf5<K, V> {
+    @BeforeTemplate
+    Map<K, V> before(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) {
+      return Map.of(k1, v1, k2, v2, k3, v3, k4, v4, k5, v5);
+    }
+
+    @AfterTemplate
+    ImmutableMap<K, V> after(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) {
+      return ImmutableMap.of(k1, v1, k2, v2, k3, v3, k4, v4, k5, v5);
     }
   }
 

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/ImmutableMultisetTemplates.java

@@ -1,12 +1,10 @@
 package tech.picnic.errorprone.refastertemplates;
 
 import static com.google.common.collect.ImmutableMultiset.toImmutableMultiset;
-import static java.util.stream.Collectors.collectingAndThen;
-import static java.util.stream.Collectors.toList;
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
 
 import com.google.common.collect.ImmutableMultiset;
 import com.google.common.collect.Streams;
-import com.google.errorprone.refaster.ImportPolicy;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
@@ -54,14 +52,11 @@ final class ImmutableMultisetTemplates {
    * alternatives.
    */
   static final class IterableToImmutableMultiset<T> {
-    // XXX: Drop the inner `Refaster.anyOf` if/when we introduce a rule to choose between one and
-    // the other.
     @BeforeTemplate
     ImmutableMultiset<T> before(T[] iterable) {
       return Refaster.anyOf(
           ImmutableMultiset.<T>builder().add(iterable).build(),
-          Refaster.anyOf(Stream.of(iterable), Arrays.stream(iterable))
-              .collect(toImmutableMultiset()));
+          Arrays.stream(iterable).collect(toImmutableMultiset()));
     }
 
     @BeforeTemplate
@@ -93,29 +88,13 @@ final class ImmutableMultisetTemplates {
   static final class StreamToImmutableMultiset<T> {
     @BeforeTemplate
     ImmutableMultiset<T> before(Stream<T> stream) {
-      return Refaster.anyOf(
-          ImmutableMultiset.copyOf(stream.iterator()),
-          ImmutableMultiset.copyOf(stream::iterator),
-          stream.collect(collectingAndThen(toList(), ImmutableMultiset::copyOf)));
+      return ImmutableMultiset.copyOf(stream.iterator());
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ImmutableMultiset<T> after(Stream<T> stream) {
       return stream.collect(toImmutableMultiset());
     }
   }
-
-  /** Don't unnecessarily copy an {@link ImmutableMultiset}. */
-  static final class ImmutableMultisetCopyOfImmutableMultiset<T> {
-    @BeforeTemplate
-    ImmutableMultiset<T> before(ImmutableMultiset<T> multiset) {
-      return ImmutableMultiset.copyOf(multiset);
-    }
-
-    @AfterTemplate
-    ImmutableMultiset<T> after(ImmutableMultiset<T> multiset) {
-      return multiset;
-    }
-  }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/ImmutableSetMultimapTemplates.java

@@ -2,6 +2,7 @@ package tech.picnic.errorprone.refastertemplates;
 
 import static com.google.common.collect.ImmutableSetMultimap.flatteningToImmutableSetMultimap;
 import static com.google.common.collect.ImmutableSetMultimap.toImmutableSetMultimap;
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
 
 import com.google.common.collect.ImmutableSetMultimap;
 import com.google.common.collect.ListMultimap;
@@ -10,7 +11,6 @@ import com.google.common.collect.Multimaps;
 import com.google.common.collect.SetMultimap;
 import com.google.common.collect.SortedSetMultimap;
 import com.google.common.collect.Streams;
-import com.google.errorprone.refaster.ImportPolicy;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
@@ -138,7 +138,7 @@ final class ImmutableSetMultimapTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ImmutableSetMultimap<K, V> after(Stream<E> stream) {
       return stream.collect(toImmutableSetMultimap(e -> keyFunction(e), e -> valueFunction(e)));
     }
@@ -162,7 +162,7 @@ final class ImmutableSetMultimapTemplates {
     @AfterTemplate
     ImmutableSetMultimap<K, V2> after(Multimap<K, V1> multimap) {
       return ImmutableSetMultimap.copyOf(
-          Multimaps.transformValues(multimap, v -> valueTransformation(v)));
+          Multimaps.transformValues(multimap, e -> valueTransformation(e)));
     }
   }
 
@@ -215,17 +215,4 @@ final class ImmutableSetMultimapTemplates {
       return ImmutableSetMultimap.copyOf(Multimaps.transformValues(multimap, transformation));
     }
   }
-
-  /** Don't unnecessarily copy an {@link ImmutableSetMultimap}. */
-  static final class ImmutableSetMultimapCopyOfImmutableSetMultimap<K, V> {
-    @BeforeTemplate
-    ImmutableSetMultimap<K, V> before(ImmutableSetMultimap<K, V> multimap) {
-      return ImmutableSetMultimap.copyOf(multimap);
-    }
-
-    @AfterTemplate
-    ImmutableSetMultimap<K, V> after(ImmutableSetMultimap<K, V> multimap) {
-      return multimap;
-    }
-  }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/ImmutableSetTemplates.java

@@ -1,21 +1,19 @@
 package tech.picnic.errorprone.refastertemplates;
 
 import static com.google.common.collect.ImmutableSet.toImmutableSet;
-import static java.util.stream.Collectors.collectingAndThen;
-import static java.util.stream.Collectors.toList;
-import static java.util.stream.Collectors.toSet;
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
+import static java.util.Collections.emptySet;
+import static java.util.Collections.singleton;
 
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Sets.SetView;
 import com.google.common.collect.Streams;
-import com.google.errorprone.refaster.ImportPolicy;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import com.google.errorprone.refaster.annotation.UseImportPolicy;
 import java.util.Arrays;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.Iterator;
 import java.util.Set;
 import java.util.stream.Stream;
@@ -39,46 +37,13 @@ final class ImmutableSetTemplates {
     }
   }
 
-  /** Prefer {@link ImmutableSet#of()} over more contrived alternatives. */
-  static final class EmptyImmutableSet<T> {
-    @BeforeTemplate
-    ImmutableSet<T> before() {
-      return Refaster.anyOf(
-          ImmutableSet.<T>builder().build(), Stream.<T>empty().collect(toImmutableSet()));
-    }
-
-    @AfterTemplate
-    ImmutableSet<T> after() {
-      return ImmutableSet.of();
-    }
-  }
-
-  /**
-   * Prefer {@link ImmutableSet#of(Object)} over alternatives that don't communicate the
-   * immutability of the resulting set at the type level.
-   */
-  // XXX: Note that this rewrite rule is incorrect for nullable elements.
-  static final class SingletonImmutableSet<T> {
-    @BeforeTemplate
-    Set<T> before(T element) {
-      return Collections.singleton(element);
-    }
-
-    @AfterTemplate
-    ImmutableSet<T> after(T element) {
-      return ImmutableSet.of(element);
-    }
-  }
-
   /** Prefer {@link ImmutableSet#copyOf(Iterable)} and variants over more contrived alternatives. */
   static final class IterableToImmutableSet<T> {
-    // XXX: Drop the inner `Refaster.anyOf` if/when we introduce a rule to choose between one and
-    // the other.
     @BeforeTemplate
     ImmutableSet<T> before(T[] iterable) {
       return Refaster.anyOf(
           ImmutableSet.<T>builder().add(iterable).build(),
-          Refaster.anyOf(Stream.of(iterable), Arrays.stream(iterable)).collect(toImmutableSet()));
+          Arrays.stream(iterable).collect(toImmutableSet()));
     }
 
     @BeforeTemplate
@@ -107,41 +72,20 @@ final class ImmutableSetTemplates {
   }
 
   /** Prefer {@link ImmutableSet#toImmutableSet()} over less idiomatic alternatives. */
-  // XXX: Once the code base has been sufficiently cleaned up, we might want to also rewrite
-  // `Collectors.toSet(`), with the caveat that it allows mutation (though this cannot be relied
-  // upon) as well as nulls. Another option is to explicitly rewrite those variants to
-  // `Collectors.toSet(HashSet::new)`.
   static final class StreamToImmutableSet<T> {
     @BeforeTemplate
     ImmutableSet<T> before(Stream<T> stream) {
       return Refaster.anyOf(
-          ImmutableSet.copyOf(stream.iterator()),
-          ImmutableSet.copyOf(stream::iterator),
-          stream.distinct().collect(toImmutableSet()),
-          stream.collect(collectingAndThen(toList(), ImmutableSet::copyOf)),
-          stream.collect(collectingAndThen(toSet(), ImmutableSet::copyOf)));
+          ImmutableSet.copyOf(stream.iterator()), stream.distinct().collect(toImmutableSet()));
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ImmutableSet<T> after(Stream<T> stream) {
       return stream.collect(toImmutableSet());
     }
   }
 
-  /** Don't unnecessarily copy an {@link ImmutableSet}. */
-  static final class ImmutableSetCopyOfImmutableSet<T> {
-    @BeforeTemplate
-    ImmutableSet<T> before(ImmutableSet<T> set) {
-      return ImmutableSet.copyOf(set);
-    }
-
-    @AfterTemplate
-    ImmutableSet<T> after(ImmutableSet<T> set) {
-      return set;
-    }
-  }
-
   /** Prefer {@link SetView#immutableCopy()} over the more verbose alternative. */
   static final class ImmutableSetCopyOfSetView<T> {
     @BeforeTemplate
@@ -154,4 +98,115 @@ final class ImmutableSetTemplates {
       return set.immutableCopy();
     }
   }
+
+  /**
+   * Prefer {@link ImmutableSet#of()} over more contrived alternatives or alternatives that don't
+   * communicate the immutability of the resulting set at the type level.
+   */
+  // XXX: The `Stream` variant may be too contrived to warrant inclusion. Review its usage if/when
+  // this and similar Refaster templates are replaced with an Error Prone check.
+  static final class ImmutableSetOf<T> {
+    @BeforeTemplate
+    Set<T> before() {
+      return Refaster.anyOf(
+          ImmutableSet.<T>builder().build(),
+          Stream.<T>empty().collect(toImmutableSet()),
+          emptySet(),
+          Set.of());
+    }
+
+    @AfterTemplate
+    ImmutableSet<T> after() {
+      return ImmutableSet.of();
+    }
+  }
+
+  /**
+   * Prefer {@link ImmutableSet#of(Object)} over more contrived alternatives or alternatives that
+   * don't communicate the immutability of the resulting set at the type level.
+   */
+  // XXX: Note that the replacement of `Collections#singleton` is incorrect for nullable elements.
+  static final class ImmutableSetOf1<T> {
+    @BeforeTemplate
+    Set<T> before(T e1) {
+      return Refaster.anyOf(ImmutableSet.<T>builder().add(e1).build(), singleton(e1), Set.of(e1));
+    }
+
+    @AfterTemplate
+    ImmutableSet<T> after(T e1) {
+      return ImmutableSet.of(e1);
+    }
+  }
+
+  /**
+   * Prefer {@link ImmutableSet#of(Object, Object)} over alternatives that don't communicate the
+   * immutability of the resulting set at the type level.
+   */
+  // XXX: Consider writing an Error Prone check which also flags straightforward
+  // `ImmutableSet.builder()` usages.
+  static final class ImmutableSetOf2<T> {
+    @BeforeTemplate
+    Set<T> before(T e1, T e2) {
+      return Set.of(e1, e2);
+    }
+
+    @AfterTemplate
+    ImmutableSet<T> after(T e1, T e2) {
+      return ImmutableSet.of(e1, e2);
+    }
+  }
+
+  /**
+   * Prefer {@link ImmutableSet#of(Object, Object, Object)} over alternatives that don't communicate
+   * the immutability of the resulting set at the type level.
+   */
+  // XXX: Consider writing an Error Prone check which also flags straightforward
+  // `ImmutableSet.builder()` usages.
+  static final class ImmutableSetOf3<T> {
+    @BeforeTemplate
+    Set<T> before(T e1, T e2, T e3) {
+      return Set.of(e1, e2, e3);
+    }
+
+    @AfterTemplate
+    ImmutableSet<T> after(T e1, T e2, T e3) {
+      return ImmutableSet.of(e1, e2, e3);
+    }
+  }
+
+  /**
+   * Prefer {@link ImmutableSet#of(Object, Object, Object, Object)} over alternatives that don't
+   * communicate the immutability of the resulting set at the type level.
+   */
+  // XXX: Consider writing an Error Prone check which also flags straightforward
+  // `ImmutableSet.builder()` usages.
+  static final class ImmutableSetOf4<T> {
+    @BeforeTemplate
+    Set<T> before(T e1, T e2, T e3, T e4) {
+      return Set.of(e1, e2, e3, e4);
+    }
+
+    @AfterTemplate
+    ImmutableSet<T> after(T e1, T e2, T e3, T e4) {
+      return ImmutableSet.of(e1, e2, e3, e4);
+    }
+  }
+
+  /**
+   * Prefer {@link ImmutableSet#of(Object, Object, Object, Object, Object)} over alternatives that
+   * don't communicate the immutability of the resulting set at the type level.
+   */
+  // XXX: Consider writing an Error Prone check which also flags straightforward
+  // `ImmutableSet.builder()` usages.
+  static final class ImmutableSetOf5<T> {
+    @BeforeTemplate
+    Set<T> before(T e1, T e2, T e3, T e4, T e5) {
+      return Set.of(e1, e2, e3, e4, e5);
+    }
+
+    @AfterTemplate
+    ImmutableSet<T> after(T e1, T e2, T e3, T e4, T e5) {
+      return ImmutableSet.of(e1, e2, e3, e4, e5);
+    }
+  }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/ImmutableSortedMapTemplates.java

@@ -108,8 +108,7 @@ final class ImmutableSortedMapTemplates {
           ImmutableSortedMap.<K, V>naturalOrder().put(entry).build(),
           Stream.of(entry)
               .collect(
-                  toImmutableSortedMap(
-                      Comparator.<K>naturalOrder(), Map.Entry::getKey, Map.Entry::getValue)));
+                  toImmutableSortedMap(naturalOrder(), Map.Entry::getKey, Map.Entry::getValue)));
     }
 
     @AfterTemplate

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/ImmutableSortedMultisetTemplates.java

@@ -1,14 +1,11 @@
 package tech.picnic.errorprone.refastertemplates;
 
 import static com.google.common.collect.ImmutableSortedMultiset.toImmutableSortedMultiset;
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
 import static java.util.Comparator.naturalOrder;
-import static java.util.stream.Collectors.collectingAndThen;
-import static java.util.stream.Collectors.toList;
 
-import com.google.common.collect.ImmutableMultiset;
 import com.google.common.collect.ImmutableSortedMultiset;
 import com.google.common.collect.Streams;
-import com.google.errorprone.refaster.ImportPolicy;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
@@ -92,18 +89,15 @@ final class ImmutableSortedMultisetTemplates {
   // XXX: There's also a variant with a custom Comparator. (And some special cases with
   // `reverseOrder`.) Worth the hassle?
   static final class IterableToImmutableSortedMultiset<T extends Comparable<? super T>> {
-    // XXX: Drop the inner `Refaster.anyOf` if/when we introduce a rule to choose between one and
-    // the other.
     @BeforeTemplate
-    ImmutableMultiset<T> before(T[] iterable) {
+    ImmutableSortedMultiset<T> before(T[] iterable) {
       return Refaster.anyOf(
           ImmutableSortedMultiset.<T>naturalOrder().add(iterable).build(),
-          Refaster.anyOf(Stream.of(iterable), Arrays.stream(iterable))
-              .collect(toImmutableSortedMultiset(naturalOrder())));
+          Arrays.stream(iterable).collect(toImmutableSortedMultiset(naturalOrder())));
     }
 
     @BeforeTemplate
-    ImmutableMultiset<T> before(Iterator<T> iterable) {
+    ImmutableSortedMultiset<T> before(Iterator<T> iterable) {
       return Refaster.anyOf(
           ImmutableSortedMultiset.copyOf(naturalOrder(), iterable),
           ImmutableSortedMultiset.<T>naturalOrder().addAll(iterable).build(),
@@ -111,7 +105,7 @@ final class ImmutableSortedMultisetTemplates {
     }
 
     @BeforeTemplate
-    ImmutableMultiset<T> before(Iterable<T> iterable) {
+    ImmutableSortedMultiset<T> before(Iterable<T> iterable) {
       return Refaster.anyOf(
           ImmutableSortedMultiset.copyOf(naturalOrder(), iterable),
           ImmutableSortedMultiset.<T>naturalOrder().addAll(iterable).build(),
@@ -130,21 +124,18 @@ final class ImmutableSortedMultisetTemplates {
   }
 
   /**
-   * Prefer {@link ImmutableSortedMultiset#toImmutableSortedMultiset(java.util.Comparator)} over
-   * less idiomatic alternatives.
+   * Prefer {@link ImmutableSortedMultiset#toImmutableSortedMultiset(Comparator)} over less
+   * idiomatic alternatives.
    */
   // XXX: Also handle the variant with a custom comparator.
   static final class StreamToImmutableSortedMultiset<T extends Comparable<? super T>> {
     @BeforeTemplate
     ImmutableSortedMultiset<T> before(Stream<T> stream) {
-      return Refaster.anyOf(
-          ImmutableSortedMultiset.copyOf(stream.iterator()),
-          ImmutableSortedMultiset.copyOf(stream::iterator),
-          stream.collect(collectingAndThen(toList(), ImmutableSortedMultiset::copyOf)));
+      return ImmutableSortedMultiset.copyOf(stream.iterator());
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ImmutableSortedMultiset<T> after(Stream<T> stream) {
       return stream.collect(toImmutableSortedMultiset(naturalOrder()));
     }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/ImmutableSortedSetTemplates.java

@@ -1,14 +1,11 @@
 package tech.picnic.errorprone.refastertemplates;
 
 import static com.google.common.collect.ImmutableSortedSet.toImmutableSortedSet;
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
 import static java.util.Comparator.naturalOrder;
-import static java.util.stream.Collectors.collectingAndThen;
-import static java.util.stream.Collectors.toList;
 
-import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.ImmutableSortedSet;
 import com.google.common.collect.Streams;
-import com.google.errorprone.refaster.ImportPolicy;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
@@ -90,18 +87,15 @@ final class ImmutableSortedSetTemplates {
   // XXX: There's also a variant with a custom Comparator. (And some special cases with
   // `reverseOrder`.) Worth the hassle?
   static final class IterableToImmutableSortedSet<T extends Comparable<? super T>> {
-    // XXX: Drop the inner `Refaster.anyOf` if/when we introduce a rule to choose between one and
-    // the other.
     @BeforeTemplate
-    ImmutableSet<T> before(T[] iterable) {
+    ImmutableSortedSet<T> before(T[] iterable) {
       return Refaster.anyOf(
           ImmutableSortedSet.<T>naturalOrder().add(iterable).build(),
-          Refaster.anyOf(Stream.of(iterable), Arrays.stream(iterable))
-              .collect(toImmutableSortedSet(naturalOrder())));
+          Arrays.stream(iterable).collect(toImmutableSortedSet(naturalOrder())));
     }
 
     @BeforeTemplate
-    ImmutableSet<T> before(Iterator<T> iterable) {
+    ImmutableSortedSet<T> before(Iterator<T> iterable) {
       return Refaster.anyOf(
           ImmutableSortedSet.copyOf(naturalOrder(), iterable),
           ImmutableSortedSet.<T>naturalOrder().addAll(iterable).build(),
@@ -109,7 +103,7 @@ final class ImmutableSortedSetTemplates {
     }
 
     @BeforeTemplate
-    ImmutableSet<T> before(Iterable<T> iterable) {
+    ImmutableSortedSet<T> before(Iterable<T> iterable) {
       return Refaster.anyOf(
           ImmutableSortedSet.copyOf(naturalOrder(), iterable),
           ImmutableSortedSet.<T>naturalOrder().addAll(iterable).build(),
@@ -128,8 +122,8 @@ final class ImmutableSortedSetTemplates {
   }
 
   /**
-   * Prefer {@link ImmutableSortedSet#toImmutableSortedSet(java.util.Comparator)} over less
-   * idiomatic alternatives.
+   * Prefer {@link ImmutableSortedSet#toImmutableSortedSet(Comparator)} over less idiomatic
+   * alternatives.
    */
   // XXX: Also handle the variant with a custom comparator.
   // XXX: Note that this rule rewrites fewer expressions than `StreamToImmutableSet`, because
@@ -137,14 +131,11 @@ final class ImmutableSortedSetTemplates {
   static final class StreamToImmutableSortedSet<T extends Comparable<? super T>> {
     @BeforeTemplate
     ImmutableSortedSet<T> before(Stream<T> stream) {
-      return Refaster.anyOf(
-          ImmutableSortedSet.copyOf(stream.iterator()),
-          ImmutableSortedSet.copyOf(stream::iterator),
-          stream.collect(collectingAndThen(toList(), ImmutableSortedSet::copyOf)));
+      return ImmutableSortedSet.copyOf(stream.iterator());
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ImmutableSortedSet<T> after(Stream<T> stream) {
       return stream.collect(toImmutableSortedSet(naturalOrder()));
     }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/IntStreamTemplates.java

@@ -6,6 +6,7 @@ import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import com.google.errorprone.refaster.annotation.MayOptionallyUse;
 import com.google.errorprone.refaster.annotation.Placeholder;
+import java.util.OptionalInt;
 import java.util.function.IntFunction;
 import java.util.function.IntPredicate;
 import java.util.function.IntUnaryOperator;
@@ -185,6 +186,18 @@ final class IntStreamTemplates {
     }
   }
 
+  static final class IntStreamMin {
+    @BeforeTemplate
+    OptionalInt before(IntStream stream) {
+      return stream.sorted().findFirst();
+    }
+
+    @AfterTemplate
+    OptionalInt after(IntStream stream) {
+      return stream.min();
+    }
+  }
+
   /** Prefer {@link IntStream#noneMatch(IntPredicate)} over more contrived alternatives. */
   static final class IntStreamNoneMatch {
     @BeforeTemplate
@@ -233,10 +246,7 @@ final class IntStreamTemplates {
   static final class IntStreamAllMatch {
     @BeforeTemplate
     boolean before(IntStream stream, IntPredicate predicate) {
-      return Refaster.anyOf(
-          stream.noneMatch(predicate.negate()),
-          !stream.anyMatch(predicate.negate()),
-          stream.filter(predicate.negate()).findAny().isEmpty());
+      return stream.noneMatch(predicate.negate());
     }
 
     @AfterTemplate
@@ -251,10 +261,7 @@ final class IntStreamTemplates {
 
     @BeforeTemplate
     boolean before(IntStream stream) {
-      return Refaster.anyOf(
-          stream.noneMatch(e -> !test(e)),
-          !stream.anyMatch(e -> !test(e)),
-          stream.filter(e -> !test(e)).findAny().isEmpty());
+      return stream.noneMatch(e -> !test(e));
     }
 
     @AfterTemplate

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/JUnitTemplates.java

@@ -0,0 +1,29 @@
+package tech.picnic.errorprone.refastertemplates;
+
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
+import static org.junit.jupiter.params.provider.Arguments.arguments;
+
+import com.google.errorprone.refaster.annotation.AfterTemplate;
+import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import com.google.errorprone.refaster.annotation.Repeated;
+import com.google.errorprone.refaster.annotation.UseImportPolicy;
+import org.junit.jupiter.params.provider.Arguments;
+
+/** Refaster templates related to JUnit expressions and statements. */
+final class JUnitTemplates {
+  private JUnitTemplates() {}
+
+  /** Prefer statically imported {@link Arguments#arguments} over {@link Arguments#of} calls. */
+  static final class ArgumentsEnumeration<T> {
+    @BeforeTemplate
+    Arguments before(@Repeated T objects) {
+      return Arguments.of(objects);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    Arguments after(@Repeated T objects) {
+      return arguments(objects);
+    }
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/LongStreamTemplates.java

@@ -6,6 +6,7 @@ import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import com.google.errorprone.refaster.annotation.MayOptionallyUse;
 import com.google.errorprone.refaster.annotation.Placeholder;
+import java.util.OptionalLong;
 import java.util.function.LongFunction;
 import java.util.function.LongPredicate;
 import java.util.function.LongUnaryOperator;
@@ -185,6 +186,18 @@ final class LongStreamTemplates {
     }
   }
 
+  static final class LongStreamMin {
+    @BeforeTemplate
+    OptionalLong before(LongStream stream) {
+      return stream.sorted().findFirst();
+    }
+
+    @AfterTemplate
+    OptionalLong after(LongStream stream) {
+      return stream.min();
+    }
+  }
+
   /** Prefer {@link LongStream#noneMatch(LongPredicate)} over more contrived alternatives. */
   static final class LongStreamNoneMatch {
     @BeforeTemplate
@@ -233,10 +246,7 @@ final class LongStreamTemplates {
   static final class LongStreamAllMatch {
     @BeforeTemplate
     boolean before(LongStream stream, LongPredicate predicate) {
-      return Refaster.anyOf(
-          stream.noneMatch(predicate.negate()),
-          !stream.anyMatch(predicate.negate()),
-          stream.filter(predicate.negate()).findAny().isEmpty());
+      return stream.noneMatch(predicate.negate());
     }
 
     @AfterTemplate
@@ -251,10 +261,7 @@ final class LongStreamTemplates {
 
     @BeforeTemplate
     boolean before(LongStream stream) {
-      return Refaster.anyOf(
-          stream.noneMatch(e -> !test(e)),
-          !stream.anyMatch(e -> !test(e)),
-          stream.filter(e -> !test(e)).findAny().isEmpty());
+      return stream.noneMatch(e -> !test(e));
     }
 
     @AfterTemplate

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/MapEntryTemplates.java

@@ -1,7 +1,12 @@
 package tech.picnic.errorprone.refastertemplates;
 
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
+import static java.util.Comparator.comparing;
+import static java.util.Comparator.naturalOrder;
+import static java.util.Map.Entry.comparingByKey;
+import static java.util.Map.Entry.comparingByValue;
+
 import com.google.common.collect.Maps;
-import com.google.errorprone.refaster.ImportPolicy;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
@@ -42,15 +47,13 @@ final class MapEntryTemplates {
   static final class MapEntryComparingByKey<K extends Comparable<? super K>, V> {
     @BeforeTemplate
     Comparator<Map.Entry<K, V>> before() {
-      return Refaster.anyOf(
-          Comparator.comparing(Map.Entry::getKey),
-          Map.Entry.comparingByKey(Comparator.naturalOrder()));
+      return Refaster.anyOf(comparing(Map.Entry::getKey), comparingByKey(naturalOrder()));
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     Comparator<Map.Entry<K, V>> after() {
-      return Map.Entry.comparingByKey();
+      return comparingByKey();
     }
   }
 
@@ -58,13 +61,13 @@ final class MapEntryTemplates {
   static final class MapEntryComparingByKeyWithCustomComparator<K, V> {
     @BeforeTemplate
     Comparator<Map.Entry<K, V>> before(Comparator<? super K> cmp) {
-      return Comparator.comparing(Map.Entry::getKey, cmp);
+      return comparing(Map.Entry::getKey, cmp);
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     Comparator<Map.Entry<K, V>> after(Comparator<? super K> cmp) {
-      return Map.Entry.comparingByKey(cmp);
+      return comparingByKey(cmp);
     }
   }
 
@@ -73,15 +76,13 @@ final class MapEntryTemplates {
   static final class MapEntryComparingByValue<K, V extends Comparable<? super V>> {
     @BeforeTemplate
     Comparator<Map.Entry<K, V>> before() {
-      return Refaster.anyOf(
-          Comparator.comparing(Map.Entry::getValue),
-          Map.Entry.comparingByValue(Comparator.naturalOrder()));
+      return Refaster.anyOf(comparing(Map.Entry::getValue), comparingByValue(naturalOrder()));
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     Comparator<Map.Entry<K, V>> after() {
-      return Map.Entry.comparingByValue();
+      return comparingByValue();
     }
   }
 
@@ -89,13 +90,13 @@ final class MapEntryTemplates {
   static final class MapEntryComparingByValueWithCustomComparator<K, V> {
     @BeforeTemplate
     Comparator<Map.Entry<K, V>> before(Comparator<? super V> cmp) {
-      return Comparator.comparing(Map.Entry::getValue, cmp);
+      return comparing(Map.Entry::getValue, cmp);
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     Comparator<Map.Entry<K, V>> after(Comparator<? super V> cmp) {
-      return Map.Entry.comparingByValue(cmp);
+      return comparingByValue(cmp);
     }
   }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/MockitoTemplates.java

@@ -0,0 +1,51 @@
+package tech.picnic.errorprone.refastertemplates;
+
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+
+import com.google.errorprone.refaster.annotation.AfterTemplate;
+import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import com.google.errorprone.refaster.annotation.UseImportPolicy;
+import org.mockito.Mockito;
+import org.mockito.verification.VerificationMode;
+
+/** Refaster templates related to Mockito expressions and statements. */
+final class MockitoTemplates {
+  private MockitoTemplates() {}
+
+  /**
+   * Prefer {@link Mockito#never()}} over explicitly specifying that the associated invocation must
+   * happen precisely zero times.
+   */
+  static final class Never {
+    @BeforeTemplate
+    VerificationMode before() {
+      return times(0);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    VerificationMode after() {
+      return never();
+    }
+  }
+
+  /**
+   * Prefer {@link Mockito#verify(Object)} over explicitly specifying that the associated invocation
+   * must happen precisely once; this is the default behavior.
+   */
+  static final class VerifyOnce<T> {
+    @BeforeTemplate
+    T before(T mock) {
+      return verify(mock, times(1));
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    T after(T mock) {
+      return verify(mock);
+    }
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/NullTemplates.java

@@ -1,7 +1,9 @@
 package tech.picnic.errorprone.refastertemplates;
 
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
+import static java.util.Objects.requireNonNullElse;
+
 import com.google.common.base.MoreObjects;
-import com.google.errorprone.refaster.ImportPolicy;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import com.google.errorprone.refaster.annotation.UseImportPolicy;
@@ -22,9 +24,9 @@ final class NullTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     T after(T first, T second) {
-      return Objects.requireNonNullElse(first, second);
+      return requireNonNullElse(first, second);
     }
   }
 

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/OptionalTemplates.java

@@ -1,7 +1,8 @@
 package tech.picnic.errorprone.refastertemplates;
 
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
+
 import com.google.common.collect.Streams;
-import com.google.errorprone.refaster.ImportPolicy;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
@@ -14,17 +15,18 @@ import java.util.function.Function;
 import java.util.function.Predicate;
 import java.util.function.Supplier;
 import java.util.stream.Stream;
+import javax.annotation.Nullable;
 
 /** Refaster templates related to expressions dealing with {@link Optional}s. */
 final class OptionalTemplates {
   private OptionalTemplates() {}
 
   static final class OptionalOfNullable<T> {
-    @BeforeTemplate
     // XXX: Refaster should be smart enough to also rewrite occurrences in which there are
     // parentheses around the null check, but that's currently not the case. Try to fix that.
-    // XXX: This is a special case of `TernaryOperatorOptionalNegativeFiltering`.
-    Optional<T> before(T object) {
+    @BeforeTemplate
+    @SuppressWarnings("TernaryOperatorOptionalNegativeFiltering" /* Special case. */)
+    Optional<T> before(@Nullable T object) {
       return object == null ? Optional.empty() : Optional.of(object);
     }
 
@@ -60,16 +62,34 @@ final class OptionalTemplates {
     }
   }
 
-  /** Prefer {@link Optional#stream()} over the Guava alternative. */
-  static final class OptionalToStream<T> {
+  /** Prefer {@link Optional#orElseThrow()} over the less explicit {@link Optional#get()}. */
+  static final class OptionalOrElseThrow<T> {
     @BeforeTemplate
-    Stream<T> before(Optional<T> optional) {
-      return Streams.stream(optional);
+    @SuppressWarnings("NullAway")
+    T before(Optional<T> optional) {
+      return optional.get();
     }
 
     @AfterTemplate
-    Stream<T> after(Optional<T> optional) {
-      return optional.stream();
+    T after(Optional<T> optional) {
+      return optional.orElseThrow();
+    }
+  }
+
+  /** Prefer {@link Optional#orElseThrow()} over the less explicit {@link Optional#get()}. */
+  // XXX: This template is analogous to `OptionalOrElseThrow` above. Arguably this is its
+  // generalization. If/when Refaster is extended to understand this, delete the template above.
+  static final class OptionalOrElseThrowMethodReference<T> {
+    @BeforeTemplate
+    @SuppressWarnings("NoFunctionalReturnType")
+    Function<Optional<T>, T> before() {
+      return Optional::get;
+    }
+
+    @AfterTemplate
+    @SuppressWarnings("NoFunctionalReturnType")
+    Function<Optional<T>, T> after() {
+      return Optional::orElseThrow;
     }
   }
 
@@ -84,7 +104,7 @@ final class OptionalTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     Optional<T> after(Iterator<T> it) {
       return Streams.stream(it).findFirst();
     }
@@ -93,7 +113,7 @@ final class OptionalTemplates {
   /** Prefer {@link Optional#filter(Predicate)} over usage of the ternary operator. */
   // XXX: This rule may introduce a compilation error: the `test` expression may reference a
   // non-effectively final variable, which is not allowed in the replacement lambda expression.
-  // Maybe our RefasterCheck should test `compilesWithFix`?
+  // Maybe our `Refaster` checker should test `compilesWithFix`?
   abstract static class TernaryOperatorOptionalPositiveFiltering<T> {
     @Placeholder
     abstract boolean test(T value);
@@ -113,7 +133,7 @@ final class OptionalTemplates {
   /** Prefer {@link Optional#filter(Predicate)} over usage of the ternary operator. */
   // XXX: This rule may introduce a compilation error: the `test` expression may reference a
   // non-effectively final variable, which is not allowed in the replacement lambda expression.
-  // Maybe our RefasterCheck should test `compilesWithFix`?
+  // Maybe our `Refaster` checker should test `compilesWithFix`?
   abstract static class TernaryOperatorOptionalNegativeFiltering<T> {
     @Placeholder
     abstract boolean test(T value);
@@ -146,12 +166,17 @@ final class OptionalTemplates {
     }
   }
 
+  /**
+   * Prefer {@link Optional#map} over a {@link Optional#flatMap} which wraps the result of a
+   * transformation in an {@link Optional}; the former operation transforms {@code null} to {@link
+   * Optional#empty()}.
+   */
   abstract static class MapToNullable<T, S> {
     @Placeholder
     abstract S toNullableFunction(@MayOptionallyUse T element);
 
     @BeforeTemplate
-    Optional<S> before(Optional<T> optional, S object) {
+    Optional<S> before(Optional<T> optional) {
       return optional.flatMap(
           v ->
               Refaster.anyOf(
@@ -159,19 +184,19 @@ final class OptionalTemplates {
     }
 
     @AfterTemplate
-    Optional<S> after(Optional<T> optional, S object) {
+    Optional<S> after(Optional<T> optional) {
       return optional.map(v -> toNullableFunction(v));
     }
   }
 
-  abstract static class MapToOptionalGet<T, S> {
+  abstract static class FlatMapToOptional<T, S> {
     @Placeholder
     abstract Optional<S> toOptionalFunction(@MayOptionallyUse T element);
 
     @BeforeTemplate
     @SuppressWarnings("NullAway")
     Optional<S> before(Optional<T> optional) {
-      return optional.map(v -> toOptionalFunction(v).get());
+      return optional.map(v -> toOptionalFunction(v).orElseThrow());
     }
 
     @AfterTemplate
@@ -180,17 +205,17 @@ final class OptionalTemplates {
     }
   }
 
-  static final class OrElseGetToOptionalGet<T> {
+  static final class OrOrElseThrow<T> {
     @BeforeTemplate
     @SuppressWarnings("NullAway")
     T before(Optional<T> o1, Optional<T> o2) {
-      return o1.orElseGet(() -> o2.get());
+      return o1.orElseGet(() -> o2.orElseThrow());
     }
 
     @AfterTemplate
     @SuppressWarnings("NullAway")
     T after(Optional<T> o1, Optional<T> o2) {
-      return o1.or(() -> o2).get();
+      return o1.or(() -> o2).orElseThrow();
     }
   }
 
@@ -204,7 +229,8 @@ final class OptionalTemplates {
     @BeforeTemplate
     Stream<T> before(Stream<Optional<T>> stream) {
       return Refaster.anyOf(
-          stream.filter(Optional::isPresent).map(Optional::get), stream.flatMap(Streams::stream));
+          stream.filter(Optional::isPresent).map(Optional::orElseThrow),
+          stream.flatMap(Streams::stream));
     }
 
     @AfterTemplate
@@ -213,21 +239,28 @@ final class OptionalTemplates {
     }
   }
 
-  /** Within a stream's map operation unconditional {@link Optional#get()} calls can be avoided. */
-  // XXX: An alternative approach is to `.flatMap(Optional::stream)`. That may be a bit longer, but
-  // yield nicer code. Think about it.
+  /**
+   * Within a stream's map operation unconditional {@link Optional#orElseThrow()} calls can be
+   * avoided.
+   *
+   * <p><strong>Warning:</strong> this rewrite rule is not completely behavior preserving. The
+   * original code throws an exception if the mapping operation does not produce a value, while the
+   * replacement does not.
+   */
+  // XXX: An alternative approach is to use `.flatMap(Optional::stream)`. That may be a bit longer,
+  // but yields nicer code. Think about it.
   abstract static class StreamMapToOptionalGet<T, S> {
     @Placeholder
     abstract Optional<S> toOptionalFunction(@MayOptionallyUse T element);
 
     @BeforeTemplate
     @SuppressWarnings("NullAway")
-    Stream<S> before(Stream<T> stream, Optional<S> optional) {
-      return stream.map(e -> toOptionalFunction(e).get());
+    Stream<S> before(Stream<T> stream) {
+      return stream.map(e -> toOptionalFunction(e).orElseThrow());
     }
 
     @AfterTemplate
-    Stream<S> after(Stream<T> stream, Optional<S> optional) {
+    Stream<S> after(Stream<T> stream) {
       return stream.flatMap(e -> toOptionalFunction(e).stream());
     }
   }
@@ -285,6 +318,7 @@ final class OptionalTemplates {
   /** Prefer {@link Optional#or(Supplier)} over more verbose alternatives. */
   abstract static class OptionalOrOtherOptional<T> {
     @BeforeTemplate
+    @SuppressWarnings("NestedOptionals" /* Auto-fix for the `NestedOptionals` check. */)
     Optional<T> before(Optional<T> optional1, Optional<T> optional2) {
       // XXX: Note that rewriting the first and third variant will change the code's behavior if
       // `optional2` has side-effects.

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/ReactorTemplates.java

@@ -1,17 +1,25 @@
 package tech.picnic.errorprone.refastertemplates;
 
+import static com.google.common.collect.MoreCollectors.toOptional;
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
+import static org.assertj.core.api.Assertions.assertThat;
+
+import com.google.common.collect.MoreCollectors;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import com.google.errorprone.refaster.annotation.MayOptionallyUse;
+import com.google.errorprone.refaster.annotation.Placeholder;
+import com.google.errorprone.refaster.annotation.UseImportPolicy;
 import java.time.Duration;
 import java.util.Optional;
 import java.util.function.Consumer;
+import java.util.function.Function;
 import java.util.function.Predicate;
 import java.util.function.Supplier;
+import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
-import reactor.core.scheduler.Scheduler;
-import reactor.core.scheduler.Schedulers;
 import reactor.test.StepVerifier;
 import reactor.test.publisher.PublisherProbe;
 
@@ -70,7 +78,7 @@ final class ReactorTemplates {
   static final class MonoErrorSupplier<T, E extends Throwable> {
     @BeforeTemplate
     Mono<T> before(Supplier<E> supplier) {
-      return Refaster.anyOf(Mono.error(supplier::get), Mono.error(() -> supplier.get()));
+      return Mono.error(() -> supplier.get());
     }
 
     @AfterTemplate
@@ -87,7 +95,7 @@ final class ReactorTemplates {
   static final class FluxErrorSupplier<T, E extends Throwable> {
     @BeforeTemplate
     Flux<T> before(Supplier<E> supplier) {
-      return Refaster.anyOf(Flux.error(supplier::get), Flux.error(() -> supplier.get()));
+      return Flux.error(() -> supplier.get());
     }
 
     @AfterTemplate
@@ -109,6 +117,139 @@ final class ReactorTemplates {
     }
   }
 
+  /** Don't unnecessarily pass an empty publisher to {@link Mono#switchIfEmpty(Mono)}. */
+  static final class MonoSwitchIfEmptyOfEmptyPublisher<T> {
+    @BeforeTemplate
+    Mono<T> before(Mono<T> mono) {
+      return mono.switchIfEmpty(Mono.empty());
+    }
+
+    @AfterTemplate
+    Mono<T> after(Mono<T> mono) {
+      return mono;
+    }
+  }
+
+  /** Don't unnecessarily pass an empty publisher to {@link Flux#switchIfEmpty(Publisher)}. */
+  static final class FluxSwitchIfEmptyOfEmptyPublisher<T> {
+    @BeforeTemplate
+    Flux<T> before(Flux<T> flux) {
+      return flux.switchIfEmpty(Refaster.anyOf(Mono.empty(), Flux.empty()));
+    }
+
+    @AfterTemplate
+    Flux<T> after(Flux<T> flux) {
+      return flux;
+    }
+  }
+
+  /** Prefer {@link Flux#concatMap(Function)} over more contrived alternatives. */
+  static final class FluxConcatMap<T, S> {
+    @BeforeTemplate
+    Flux<S> before(Flux<T> flux, Function<? super T, ? extends Publisher<? extends S>> function) {
+      return Refaster.anyOf(flux.flatMap(function, 1), flux.flatMapSequential(function, 1));
+    }
+
+    @AfterTemplate
+    Flux<S> after(Flux<T> flux, Function<? super T, ? extends Publisher<? extends S>> function) {
+      return flux.concatMap(function);
+    }
+  }
+
+  /**
+   * Prefer {@link Flux#concatMapIterable(Function)} over {@link Flux#flatMapIterable(Function)}, as
+   * the former has equivalent semantics but a clearer name.
+   */
+  static final class FluxConcatMapIterable<T, S> {
+    @BeforeTemplate
+    Flux<S> before(Flux<T> flux, Function<? super T, ? extends Iterable<? extends S>> function) {
+      return flux.flatMapIterable(function);
+    }
+
+    @AfterTemplate
+    Flux<S> after(Flux<T> flux, Function<? super T, ? extends Iterable<? extends S>> function) {
+      return flux.concatMapIterable(function);
+    }
+  }
+
+  /**
+   * Don't use {@link Mono#flatMapMany(Function)} to implicitly convert a {@link Mono} to a {@link
+   * Flux}.
+   */
+  abstract static class MonoFlatMapToFlux<T, S> {
+    @Placeholder(allowsIdentity = true)
+    abstract Mono<S> valueTransformation(@MayOptionallyUse T value);
+
+    @BeforeTemplate
+    Flux<S> before(Mono<T> mono) {
+      return mono.flatMapMany(v -> valueTransformation(v));
+    }
+
+    @AfterTemplate
+    Flux<S> after(Mono<T> mono) {
+      return mono.flatMap(v -> valueTransformation(v)).flux();
+    }
+  }
+
+  /** Prefer {@link Mono#flux()}} over more contrived alternatives. */
+  static final class MonoFlux<T> {
+    @BeforeTemplate
+    Flux<T> before(Mono<T> mono) {
+      return Flux.concat(mono);
+    }
+
+    @AfterTemplate
+    Flux<T> after(Mono<T> mono) {
+      return mono.flux();
+    }
+  }
+
+  /**
+   * Prefer a collection using {@link MoreCollectors#toOptional()} over more contrived alternatives.
+   */
+  // XXX: Consider creating a plugin which flags/discourages `Mono<Optional<T>>` method return
+  // types, just as we discourage nullable `Boolean`s and `Optional`s.
+  static final class MonoCollectToOptional<T> {
+    @BeforeTemplate
+    Mono<Optional<T>> before(Mono<T> mono) {
+      return Refaster.anyOf(
+          mono.map(Optional::of).defaultIfEmpty(Optional.empty()),
+          mono.map(Optional::of).switchIfEmpty(Mono.just(Optional.empty())));
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    Mono<Optional<T>> after(Mono<T> mono) {
+      return mono.flux().collect(toOptional());
+    }
+  }
+
+  /** Prefer {@link Mono#cast(Class)} over {@link Mono#map(Function)} with a cast. */
+  static final class MonoCast<T, S> {
+    @BeforeTemplate
+    Mono<S> before(Mono<T> mono) {
+      return mono.map(Refaster.<S>clazz()::cast);
+    }
+
+    @AfterTemplate
+    Mono<S> after(Mono<T> mono) {
+      return mono.cast(Refaster.<S>clazz());
+    }
+  }
+
+  /** Prefer {@link Flux#cast(Class)} over {@link Flux#map(Function)} with a cast. */
+  static final class FluxCast<T, S> {
+    @BeforeTemplate
+    Flux<S> before(Flux<T> flux) {
+      return flux.map(Refaster.<S>clazz()::cast);
+    }
+
+    @AfterTemplate
+    Flux<S> after(Flux<T> flux) {
+      return flux.cast(Refaster.<S>clazz());
+    }
+  }
+
   /** Prefer {@link PublisherProbe#empty()}} over more verbose alternatives. */
   static final class PublisherProbeEmpty<T> {
     @BeforeTemplate
@@ -122,6 +263,32 @@ final class ReactorTemplates {
     }
   }
 
+  /** Prefer {@link Mono#as(Function)} when creating a {@link StepVerifier}. */
+  static final class StepVerifierFromMono<T> {
+    @BeforeTemplate
+    StepVerifier.FirstStep<? extends T> before(Mono<T> mono) {
+      return StepVerifier.create(mono);
+    }
+
+    @AfterTemplate
+    StepVerifier.FirstStep<? extends T> after(Mono<T> mono) {
+      return mono.as(StepVerifier::create);
+    }
+  }
+
+  /** Prefer {@link Flux#as(Function)} when creating a {@link StepVerifier}. */
+  static final class StepVerifierFromFlux<T> {
+    @BeforeTemplate
+    StepVerifier.FirstStep<? extends T> before(Flux<T> flux) {
+      return StepVerifier.create(flux);
+    }
+
+    @AfterTemplate
+    StepVerifier.FirstStep<? extends T> after(Flux<T> flux) {
+      return flux.as(StepVerifier::create);
+    }
+  }
+
   /** Don't unnecessarily call {@link StepVerifier.Step#expectNext(Object[])}. */
   static final class StepVerifierStepExpectNextEmpty<T> {
     @BeforeTemplate
@@ -180,7 +347,9 @@ final class ReactorTemplates {
   static final class StepVerifierLastStepVerifyErrorClass<T extends Throwable> {
     @BeforeTemplate
     Duration before(StepVerifier.LastStep step, Class<T> clazz) {
-      return step.expectError(clazz).verify();
+      return Refaster.anyOf(
+          step.expectError(clazz).verify(),
+          step.verifyErrorSatisfies(t -> assertThat(t).isInstanceOf(clazz)));
     }
 
     @AfterTemplate
@@ -250,18 +419,4 @@ final class ReactorTemplates {
       return step.verifyTimeout(duration);
     }
   }
-
-  /** Prefer {@link Schedulers#boundedElastic()} over the unbounded alternative. */
-  // XXX: Also add templates for the `Schedulers#newElastic` variants.
-  static final class BoundedElasticScheduler {
-    @BeforeTemplate
-    Scheduler before() {
-      return Schedulers.elastic();
-    }
-
-    @AfterTemplate
-    Scheduler after() {
-      return Schedulers.boundedElastic();
-    }
-  }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/RxJava2AdapterTemplates.java

@@ -41,11 +41,9 @@ final class RxJava2AdapterTemplates {
     @BeforeTemplate
     Publisher<T> before(Flowable<T> flowable) {
       return Refaster.anyOf(
-          Flux.from(flowable),
           flowable.compose(Flux::from),
           flowable.to(Flux::from),
           flowable.as(Flux::from),
-          RxJava2Adapter.flowableToFlux(flowable),
           flowable.compose(RxJava2Adapter::flowableToFlux),
           flowable.to(RxJava2Adapter::flowableToFlux));
     }
@@ -67,7 +65,6 @@ final class RxJava2AdapterTemplates {
           Flowable.fromPublisher(flux),
           flux.transform(Flowable::fromPublisher),
           flux.as(Flowable::fromPublisher),
-          RxJava2Adapter.fluxToFlowable(flux),
           flux.transform(RxJava2Adapter::fluxToFlowable));
     }
 
@@ -140,7 +137,6 @@ final class RxJava2AdapterTemplates {
           Flowable.fromPublisher(mono),
           mono.transform(Flowable::fromPublisher),
           mono.as(Flowable::fromPublisher),
-          RxJava2Adapter.monoToFlowable(mono),
           mono.transform(RxJava2Adapter::monoToFlowable));
     }
 

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/StreamTemplates.java

@@ -1,6 +1,10 @@
 package tech.picnic.errorprone.refastertemplates;
 
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
+import static java.util.Comparator.naturalOrder;
+import static java.util.Comparator.reverseOrder;
 import static java.util.function.Predicate.not;
+import static java.util.stream.Collectors.joining;
 
 import com.google.common.collect.Streams;
 import com.google.errorprone.refaster.Refaster;
@@ -8,16 +12,38 @@ import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import com.google.errorprone.refaster.annotation.MayOptionallyUse;
 import com.google.errorprone.refaster.annotation.Placeholder;
+import com.google.errorprone.refaster.annotation.UseImportPolicy;
+import java.util.Arrays;
+import java.util.Comparator;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.function.Function;
 import java.util.function.Predicate;
+import java.util.stream.Collector;
+import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 /** Refaster templates related to expressions dealing with {@link Stream}s. */
 final class StreamTemplates {
   private StreamTemplates() {}
 
+  /**
+   * Prefer {@link Collectors#joining()} over {@link Collectors#joining(CharSequence)} with an empty
+   * delimiter string.
+   */
+  static final class Joining {
+    @BeforeTemplate
+    Collector<CharSequence, ?, String> before() {
+      return joining("");
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    Collector<CharSequence, ?, String> after() {
+      return joining();
+    }
+  }
+
   /** Prefer {@link Stream#empty()} over less clear alternatives. */
   static final class EmptyStream<T> {
     @BeforeTemplate
@@ -45,6 +71,22 @@ final class StreamTemplates {
     }
   }
 
+  /**
+   * Prefer {@link Arrays#stream(Object[])} over {@link Stream#of(Object[])}, as the former is
+   * clearer.
+   */
+  static final class StreamOfArray<T> {
+    @BeforeTemplate
+    Stream<T> before(T[] array) {
+      return Stream.of(array);
+    }
+
+    @AfterTemplate
+    Stream<T> after(T[] array) {
+      return Arrays.stream(array);
+    }
+  }
+
   /** Don't unnecessarily call {@link Streams#concat(Stream...)}. */
   static final class ConcatOneStream<T> {
     @BeforeTemplate
@@ -126,6 +168,8 @@ final class StreamTemplates {
    */
   // XXX: Consider whether to have a similar rule for `.findAny()`. For parallel streams it
   // wouldn't be quite the same....
+  // XXX: This change is not equivalent for `null`-returning functions, as the original code throws
+  // an NPE if the first element is `null`, while the latter yields an empty `Optional`.
   static final class StreamMapFirst<T, S> {
     @BeforeTemplate
     Optional<S> before(Stream<T> stream, Function<? super T, S> function) {
@@ -172,6 +216,58 @@ final class StreamTemplates {
     }
   }
 
+  static final class StreamMin<T> {
+    @BeforeTemplate
+    Optional<T> before(Stream<T> stream, Comparator<? super T> comparator) {
+      return Refaster.anyOf(
+          stream.max(comparator.reversed()), stream.sorted(comparator).findFirst());
+    }
+
+    @AfterTemplate
+    Optional<T> after(Stream<T> stream, Comparator<? super T> comparator) {
+      return stream.min(comparator);
+    }
+  }
+
+  static final class StreamMinNaturalOrder<T extends Comparable<? super T>> {
+    @BeforeTemplate
+    Optional<T> before(Stream<T> stream) {
+      return Refaster.anyOf(stream.max(reverseOrder()), stream.sorted().findFirst());
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    Optional<T> after(Stream<T> stream) {
+      return stream.min(naturalOrder());
+    }
+  }
+
+  static final class StreamMax<T> {
+    @BeforeTemplate
+    Optional<T> before(Stream<T> stream, Comparator<? super T> comparator) {
+      return Refaster.anyOf(
+          stream.min(comparator.reversed()), Streams.findLast(stream.sorted(comparator)));
+    }
+
+    @AfterTemplate
+    Optional<T> after(Stream<T> stream, Comparator<? super T> comparator) {
+      return stream.max(comparator);
+    }
+  }
+
+  static final class StreamMaxNaturalOrder<T extends Comparable<? super T>> {
+    @BeforeTemplate
+    Optional<T> before(Stream<T> stream) {
+      return Refaster.anyOf(stream.min(reverseOrder()), Streams.findLast(stream.sorted()));
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    Optional<T> after(Stream<T> stream) {
+      return stream.max(naturalOrder());
+    }
+  }
+
   /** Prefer {@link Stream#noneMatch(Predicate)} over more contrived alternatives. */
   static final class StreamNoneMatch<T> {
     @BeforeTemplate
@@ -220,10 +316,7 @@ final class StreamTemplates {
   static final class StreamAllMatch<T> {
     @BeforeTemplate
     boolean before(Stream<T> stream, Predicate<? super T> predicate) {
-      return Refaster.anyOf(
-          stream.noneMatch(Refaster.anyOf(not(predicate), predicate.negate())),
-          !stream.anyMatch(Refaster.anyOf(not(predicate), predicate.negate())),
-          stream.filter(Refaster.anyOf(not(predicate), predicate.negate())).findAny().isEmpty());
+      return stream.noneMatch(Refaster.anyOf(not(predicate), predicate.negate()));
     }
 
     @AfterTemplate
@@ -238,10 +331,7 @@ final class StreamTemplates {
 
     @BeforeTemplate
     boolean before(Stream<T> stream) {
-      return Refaster.anyOf(
-          stream.noneMatch(e -> !test(e)),
-          !stream.anyMatch(e -> !test(e)),
-          stream.filter(e -> !test(e)).findAny().isEmpty());
+      return stream.noneMatch(e -> !test(e));
     }
 
     @AfterTemplate

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/StringTemplates.java

@@ -1,9 +1,11 @@
 package tech.picnic.errorprone.refastertemplates;
 
+import static java.nio.charset.StandardCharsets.UTF_8;
 import static java.util.stream.Collectors.joining;
 
 import com.google.common.base.Joiner;
 import com.google.common.base.Strings;
+import com.google.common.base.Utf8;
 import com.google.common.collect.Streams;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
@@ -12,7 +14,7 @@ import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Optional;
-import java.util.stream.Stream;
+import javax.annotation.Nullable;
 
 /** Refaster templates related to expressions dealing with {@link String}s. */
 // XXX: Should we prefer `s -> !s.isEmpty()` or `not(String::isEmpty)`?
@@ -36,7 +38,7 @@ final class StringTemplates {
   /** Prefer {@link Strings#isNullOrEmpty(String)} over the more verbose alternative. */
   static final class StringIsNullOrEmpty {
     @BeforeTemplate
-    boolean before(String str) {
+    boolean before(@Nullable String str) {
       return str == null || str.isEmpty();
     }
 
@@ -80,12 +82,10 @@ final class StringTemplates {
   // XXX: Joiner#join(@Nullable Object first, @Nullable Object second, Object... rest) isn't
   // rewritten.
   static final class JoinStrings {
-    // XXX: Drop the inner `Refaster.anyOf` if/when we decide to rewrite one to the other.
     @BeforeTemplate
     String before(String delimiter, CharSequence[] elements) {
       return Refaster.anyOf(
-          Joiner.on(delimiter).join(elements),
-          Refaster.anyOf(Stream.of(elements), Arrays.stream(elements)).collect(joining(delimiter)));
+          Joiner.on(delimiter).join(elements), Arrays.stream(elements).collect(joining(delimiter)));
     }
 
     @BeforeTemplate
@@ -96,12 +96,12 @@ final class StringTemplates {
     }
 
     @BeforeTemplate
-    String before(String delimiter, Collection<? extends CharSequence> elements) {
+    String before(CharSequence delimiter, Collection<? extends CharSequence> elements) {
       return elements.stream().collect(joining(delimiter));
     }
 
     @AfterTemplate
-    String after(String delimiter, Iterable<? extends CharSequence> elements) {
+    String after(CharSequence delimiter, Iterable<? extends CharSequence> elements) {
       return String.join(delimiter, elements);
     }
   }
@@ -118,4 +118,17 @@ final class StringTemplates {
       return str.substring(index);
     }
   }
+
+  /** Prefer {@link Utf8#encodedLength(CharSequence)} over less efficient alternatives. */
+  static final class Utf8EncodedLength {
+    @BeforeTemplate
+    int before(String str) {
+      return str.getBytes(UTF_8).length;
+    }
+
+    @AfterTemplate
+    int after(String str) {
+      return Utf8.encodedLength(str);
+    }
+  }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/TestNGToAssertJTemplates.java

@@ -1,5 +1,6 @@
 package tech.picnic.errorprone.refastertemplates;
 
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
 import static org.assertj.core.api.Assertions.fail;
@@ -16,7 +17,7 @@ import static org.testng.Assert.assertThrows;
 import static org.testng.Assert.assertTrue;
 
 import com.google.common.collect.ImmutableList;
-import com.google.errorprone.refaster.ImportPolicy;
+import com.google.errorprone.annotations.DoNotCall;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import com.google.errorprone.refaster.annotation.UseImportPolicy;
@@ -61,7 +62,7 @@ import org.testng.Assert.ThrowingRunnable;
  *         <li>{@link Assert#assertNotEqualsDeep(Set, Set)}
  *         <li>{@link Assert#assertNotEqualsDeep(Set, Set, String)}
  *       </ul>
- *   <li>This method returns the caugth exception; there is no direct counterpart for this in
+ *   <li>This method returns the caught exception; there is no direct counterpart for this in
  *       AssertJ:
  *       <ul>
  *         <li>{@link Assert#expectThrows(Class, ThrowingRunnable)}
@@ -81,6 +82,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
+    @DoNotCall
     void after() {
       throw new AssertionError();
     }
@@ -94,7 +96,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(String message) {
       fail(message);
     }
@@ -108,7 +110,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(String message, Throwable throwable) {
       fail(message, throwable);
     }
@@ -121,7 +123,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(boolean condition) {
       assertThat(condition).isTrue();
     }
@@ -134,7 +136,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(boolean condition, String message) {
       assertThat(condition).withFailMessage(message).isTrue();
     }
@@ -147,7 +149,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(boolean condition) {
       assertThat(condition).isFalse();
     }
@@ -160,7 +162,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(boolean condition, String message) {
       assertThat(condition).withFailMessage(message).isFalse();
     }
@@ -173,7 +175,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Object object) {
       assertThat(object).isNull();
     }
@@ -186,7 +188,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Object object, String message) {
       assertThat(object).withFailMessage(message).isNull();
     }
@@ -199,7 +201,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Object object) {
       assertThat(object).isNotNull();
     }
@@ -212,7 +214,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Object object, String message) {
       assertThat(object).withFailMessage(message).isNotNull();
     }
@@ -225,7 +227,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Object actual, Object expected) {
       assertThat(actual).isSameAs(expected);
     }
@@ -238,7 +240,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Object actual, Object expected, String message) {
       assertThat(actual).withFailMessage(message).isSameAs(expected);
     }
@@ -251,7 +253,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Object actual, Object expected) {
       assertThat(actual).isNotSameAs(expected);
     }
@@ -264,7 +266,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Object actual, Object expected, String message) {
       assertThat(actual).withFailMessage(message).isNotSameAs(expected);
     }
@@ -327,7 +329,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Object actual, Object expected) {
       assertThat(actual).isEqualTo(expected);
     }
@@ -390,7 +392,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Object actual, Object expected, String message) {
       assertThat(actual).withFailMessage(message).isEqualTo(expected);
     }
@@ -403,7 +405,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(float actual, float expected, float delta) {
       assertThat(actual).isCloseTo(expected, offset(delta));
     }
@@ -416,7 +418,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(float actual, float expected, float delta, String message) {
       assertThat(actual).withFailMessage(message).isCloseTo(expected, offset(delta));
     }
@@ -429,7 +431,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(double actual, double expected, double delta) {
       assertThat(actual).isCloseTo(expected, offset(delta));
     }
@@ -442,7 +444,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(double actual, double expected, double delta, String message) {
       assertThat(actual).withFailMessage(message).isCloseTo(expected, offset(delta));
     }
@@ -495,7 +497,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Object[] actual, Object[] expected) {
       assertThat(actual).containsExactly(expected);
     }
@@ -548,7 +550,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Object[] actual, Object[] expected, String message) {
       assertThat(actual).withFailMessage(message).containsExactly(expected);
     }
@@ -561,7 +563,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Object[] actual, Object[] expected) {
       assertThat(actual).containsExactlyInAnyOrder(expected);
     }
@@ -574,7 +576,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Object[] actual, Object[] expected, String message) {
       assertThat(actual).withFailMessage(message).containsExactlyInAnyOrder(expected);
     }
@@ -587,7 +589,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     <S, T extends S> void after(Iterator<S> actual, Iterator<T> expected) {
       // XXX: This is not `null`-safe.
       // XXX: The `ImmutableList.copyOf` should actually *not* be imported statically.
@@ -602,7 +604,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     <S, T extends S> void after(Iterator<S> actual, Iterator<T> expected, String message) {
       // XXX: This is not `null`-safe.
       // XXX: The `ImmutableList.copyOf` should actually *not* be imported statically.
@@ -627,7 +629,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     <S, T extends S> void after(Iterable<S> actual, Iterable<T> expected) {
       assertThat(actual).containsExactlyElementsOf(expected);
     }
@@ -645,7 +647,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     <S, T extends S> void after(Iterable<S> actual, Iterable<T> expected, String message) {
       assertThat(actual).withFailMessage(message).containsExactlyElementsOf(expected);
     }
@@ -658,7 +660,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     <S, T extends S> void after(Set<S> actual, Set<T> expected) {
       assertThat(actual).hasSameElementsAs(expected);
     }
@@ -671,7 +673,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     <S, T extends S> void after(Set<S> actual, Set<T> expected, String message) {
       assertThat(actual).withFailMessage(message).hasSameElementsAs(expected);
     }
@@ -739,7 +741,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Object actual, Object expected) {
       assertThat(actual).isNotEqualTo(expected);
     }
@@ -807,7 +809,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Object actual, Object expected, String message) {
       assertThat(actual).withFailMessage(message).isNotEqualTo(expected);
     }
@@ -820,7 +822,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(float actual, float expected, float delta) {
       assertThat(actual).isNotCloseTo(expected, offset(delta));
     }
@@ -833,7 +835,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(float actual, float expected, float delta, String message) {
       assertThat(actual).withFailMessage(message).isNotCloseTo(expected, offset(delta));
     }
@@ -846,7 +848,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(double actual, double expected, double delta) {
       assertThat(actual).isNotCloseTo(expected, offset(delta));
     }
@@ -859,7 +861,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(double actual, double expected, double delta, String message) {
       assertThat(actual).withFailMessage(message).isNotCloseTo(expected, offset(delta));
     }
@@ -872,7 +874,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(ThrowingCallable runnable) {
       assertThatThrownBy(runnable);
     }
@@ -885,7 +887,7 @@ final class TestNGToAssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(ThrowingCallable runnable, Class<T> clazz) {
       assertThatThrownBy(runnable).isInstanceOf(clazz);
     }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/TimeTemplates.java

@@ -1,5 +1,7 @@
 package tech.picnic.errorprone.refastertemplates;
 
+import static java.time.ZoneOffset.UTC;
+
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.AlsoNegation;
@@ -17,6 +19,7 @@ import java.time.ZoneOffset;
 import java.time.chrono.ChronoLocalDate;
 import java.time.chrono.ChronoLocalDateTime;
 import java.time.chrono.ChronoZonedDateTime;
+import java.time.temporal.ChronoUnit;
 import java.time.temporal.TemporalUnit;
 
 /** Refaster templates related to expressions dealing with time. */
@@ -43,30 +46,45 @@ final class TimeTemplates {
   static final class UtcConstant {
     @BeforeTemplate
     ZoneId before() {
+      // `ZoneId.of("Z")` is not listed, because Error Prone flags it out of the box.
       return Refaster.anyOf(
           ZoneId.of("GMT"),
           ZoneId.of("UTC"),
-          ZoneId.of("Z"),
           ZoneId.of("+0"),
           ZoneId.of("-0"),
-          ZoneOffset.UTC.normalized(),
-          ZoneId.from(ZoneOffset.UTC));
+          UTC.normalized(),
+          ZoneId.from(UTC));
     }
 
     @AfterTemplate
     ZoneOffset after() {
-      return ZoneOffset.UTC;
+      return UTC;
+    }
+  }
+
+  /** Prefer {@link Instant#atOffset(ZoneOffset)} over the more verbose alternative. */
+  static final class InstantAtOffset {
+    @BeforeTemplate
+    OffsetDateTime before(Instant instant, ZoneOffset zoneOffset) {
+      return OffsetDateTime.ofInstant(instant, zoneOffset);
+    }
+
+    @AfterTemplate
+    OffsetDateTime after(Instant instant, ZoneOffset zoneOffset) {
+      return instant.atOffset(zoneOffset);
     }
   }
 
   /** Use {@link Clock#systemUTC()} when possible. */
   static final class UtcClock {
     @BeforeTemplate
+    @SuppressWarnings("TimeZoneUsage")
     Clock before() {
-      return Clock.system(ZoneOffset.UTC);
+      return Clock.system(UTC);
     }
 
     @AfterTemplate
+    @SuppressWarnings("TimeZoneUsage")
     Clock after() {
       return Clock.systemUTC();
     }
@@ -96,8 +114,8 @@ final class TimeTemplates {
       return a.compareTo(b) < 0;
     }
 
-    @AlsoNegation
     @AfterTemplate
+    @AlsoNegation
     boolean after(Instant a, Instant b) {
       return a.isBefore(b);
     }
@@ -113,8 +131,8 @@ final class TimeTemplates {
       return a.compareTo(b) > 0;
     }
 
-    @AlsoNegation
     @AfterTemplate
+    @AlsoNegation
     boolean after(Instant a, Instant b) {
       return a.isAfter(b);
     }
@@ -162,8 +180,8 @@ final class TimeTemplates {
       return a.compareTo(b) < 0;
     }
 
-    @AlsoNegation
     @AfterTemplate
+    @AlsoNegation
     boolean after(ChronoLocalDate a, ChronoLocalDate b) {
       return a.isBefore(b);
     }
@@ -179,8 +197,8 @@ final class TimeTemplates {
       return a.compareTo(b) > 0;
     }
 
-    @AlsoNegation
     @AfterTemplate
+    @AlsoNegation
     boolean after(ChronoLocalDate a, ChronoLocalDate b) {
       return a.isAfter(b);
     }
@@ -196,8 +214,8 @@ final class TimeTemplates {
       return a.compareTo(b) < 0;
     }
 
-    @AlsoNegation
     @AfterTemplate
+    @AlsoNegation
     boolean after(ChronoLocalDateTime<?> a, ChronoLocalDateTime<?> b) {
       return a.isBefore(b);
     }
@@ -213,8 +231,8 @@ final class TimeTemplates {
       return a.compareTo(b) > 0;
     }
 
-    @AlsoNegation
     @AfterTemplate
+    @AlsoNegation
     boolean after(ChronoLocalDateTime<?> a, ChronoLocalDateTime<?> b) {
       return a.isAfter(b);
     }
@@ -230,8 +248,8 @@ final class TimeTemplates {
       return a.compareTo(b) < 0;
     }
 
-    @AlsoNegation
     @AfterTemplate
+    @AlsoNegation
     boolean after(ChronoZonedDateTime<?> a, ChronoZonedDateTime<?> b) {
       return a.isBefore(b);
     }
@@ -247,8 +265,8 @@ final class TimeTemplates {
       return a.compareTo(b) > 0;
     }
 
-    @AlsoNegation
     @AfterTemplate
+    @AlsoNegation
     boolean after(ChronoZonedDateTime<?> a, ChronoZonedDateTime<?> b) {
       return a.isAfter(b);
     }
@@ -264,8 +282,8 @@ final class TimeTemplates {
       return a.compareTo(b) < 0;
     }
 
-    @AlsoNegation
     @AfterTemplate
+    @AlsoNegation
     boolean after(OffsetDateTime a, OffsetDateTime b) {
       return a.isBefore(b);
     }
@@ -281,8 +299,8 @@ final class TimeTemplates {
       return a.compareTo(b) > 0;
     }
 
-    @AlsoNegation
     @AfterTemplate
+    @AlsoNegation
     boolean after(OffsetDateTime a, OffsetDateTime b) {
       return a.isAfter(b);
     }
@@ -308,8 +326,86 @@ final class TimeTemplates {
     }
   }
 
+  /** Prefer {@link Duration#ofDays(long)} over alternative representations. */
+  static final class DurationOfDays {
+    @BeforeTemplate
+    Duration before(long amount) {
+      return Duration.of(amount, ChronoUnit.DAYS);
+    }
+
+    @AfterTemplate
+    Duration after(long amount) {
+      return Duration.ofDays(amount);
+    }
+  }
+
+  /** Prefer {@link Duration#ofHours(long)} over alternative representations. */
+  static final class DurationOfHours {
+    @BeforeTemplate
+    Duration before(long amount) {
+      return Duration.of(amount, ChronoUnit.HOURS);
+    }
+
+    @AfterTemplate
+    Duration after(long amount) {
+      return Duration.ofHours(amount);
+    }
+  }
+
+  /** Prefer {@link Duration#ofMillis(long)} over alternative representations. */
+  static final class DurationOfMillis {
+    @BeforeTemplate
+    Duration before(long amount) {
+      return Duration.of(amount, ChronoUnit.MILLIS);
+    }
+
+    @AfterTemplate
+    Duration after(long amount) {
+      return Duration.ofMillis(amount);
+    }
+  }
+
+  /** Prefer {@link Duration#ofMinutes(long)} over alternative representations. */
+  static final class DurationOfMinutes {
+    @BeforeTemplate
+    Duration before(long amount) {
+      return Duration.of(amount, ChronoUnit.MINUTES);
+    }
+
+    @AfterTemplate
+    Duration after(long amount) {
+      return Duration.ofMinutes(amount);
+    }
+  }
+
+  /** Prefer {@link Duration#ofNanos(long)} over alternative representations. */
+  static final class DurationOfNanos {
+    @BeforeTemplate
+    Duration before(long amount) {
+      return Duration.of(amount, ChronoUnit.NANOS);
+    }
+
+    @AfterTemplate
+    Duration after(long amount) {
+      return Duration.ofNanos(amount);
+    }
+  }
+
+  /** Prefer {@link Duration#ofSeconds(long)} over alternative representations. */
+  static final class DurationOfSeconds {
+    @BeforeTemplate
+    Duration before(long amount) {
+      return Duration.of(amount, ChronoUnit.SECONDS);
+    }
+
+    @AfterTemplate
+    Duration after(long amount) {
+      return Duration.ofSeconds(amount);
+    }
+  }
+
   /**
-   * Don't unnecessarily convert two and from milliseconds. (This way nanosecond precision is
+   * Don't unnecessarily convert to and from milliseconds. (This way nanosecond precision is
    * retained.)
    *
    * <p><strong>Warning:</strong> this rewrite rule increases precision!
@@ -327,7 +423,7 @@ final class TimeTemplates {
   }
 
   /**
-   * Don't unnecessarily convert two and from milliseconds. (This way nanosecond precision is
+   * Don't unnecessarily convert to and from milliseconds. (This way nanosecond precision is
    * retained.)
    *
    * <p><strong>Warning:</strong> this rewrite rule increases precision!

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/WebClientTemplates.java

@@ -0,0 +1,204 @@
+package tech.picnic.errorprone.refastertemplates;
+
+import static org.springframework.http.HttpMethod.GET;
+import static org.springframework.http.HttpMethod.HEAD;
+import static org.springframework.http.HttpMethod.OPTIONS;
+import static org.springframework.http.HttpMethod.PATCH;
+import static org.springframework.http.HttpMethod.POST;
+import static org.springframework.http.HttpMethod.PUT;
+import static org.springframework.web.reactive.function.BodyInserters.fromValue;
+
+import com.google.errorprone.refaster.Refaster;
+import com.google.errorprone.refaster.annotation.AfterTemplate;
+import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import com.google.errorprone.refaster.annotation.Repeated;
+import java.util.function.Function;
+import org.springframework.http.HttpMethod;
+import org.springframework.test.web.reactive.server.WebTestClient;
+import org.springframework.web.reactive.function.client.WebClient;
+import org.springframework.web.reactive.function.client.WebClient.RequestBodySpec;
+import org.springframework.web.reactive.function.client.WebClient.RequestBodyUriSpec;
+import org.springframework.web.reactive.function.client.WebClient.RequestHeadersSpec;
+import org.springframework.web.reactive.function.client.WebClient.RequestHeadersUriSpec;
+
+/**
+ * Refaster templates related to expressions dealing with {@link
+ * org.springframework.web.reactive.function.client.WebClient} and related types.
+ */
+final class WebClientTemplates {
+  private WebClientTemplates() {}
+
+  /** Prefer {@link RequestBodySpec#bodyValue(Object)} over more contrived alternatives. */
+  static final class BodyValue<T> {
+    @BeforeTemplate
+    RequestHeadersSpec<?> before(RequestBodySpec requestBodySpec, T value) {
+      return requestBodySpec.body(fromValue(value));
+    }
+
+    @BeforeTemplate
+    WebTestClient.RequestHeadersSpec<?> before(
+        WebTestClient.RequestBodySpec requestBodySpec, T value) {
+      return requestBodySpec.body(fromValue(value));
+    }
+
+    @AfterTemplate
+    RequestHeadersSpec<?> after(RequestBodySpec requestBodySpec, T value) {
+      return requestBodySpec.bodyValue(value);
+    }
+  }
+
+  /**
+   * Prefer {@link WebClient#get()} over {@link WebClient#method(HttpMethod)} with {@link
+   * HttpMethod#GET}.
+   */
+  static final class WebClientGet {
+    @BeforeTemplate
+    RequestHeadersSpec<?> before(WebClient webClient) {
+      return webClient.method(GET);
+    }
+
+    @BeforeTemplate
+    WebTestClient.RequestHeadersSpec<?> before(WebTestClient webClient) {
+      return webClient.method(GET);
+    }
+
+    @AfterTemplate
+    RequestHeadersSpec<?> after(WebClient webClient) {
+      return webClient.get();
+    }
+  }
+
+  /**
+   * Prefer {@link WebClient#head()} over {@link WebClient#method(HttpMethod)} with {@link
+   * HttpMethod#HEAD}.
+   */
+  static final class WebClientHead {
+    @BeforeTemplate
+    RequestHeadersSpec<?> before(WebClient webClient) {
+      return webClient.method(HEAD);
+    }
+
+    @BeforeTemplate
+    WebTestClient.RequestHeadersSpec<?> before(WebTestClient webClient) {
+      return webClient.method(HEAD);
+    }
+
+    @AfterTemplate
+    RequestHeadersSpec<?> after(WebClient webClient) {
+      return webClient.head();
+    }
+  }
+
+  /**
+   * Prefer {@link WebClient#options()} over {@link WebClient#method(HttpMethod)} with {@link
+   * HttpMethod#OPTIONS}.
+   */
+  static final class WebClientOptions {
+    @BeforeTemplate
+    RequestHeadersSpec<?> before(WebClient webClient) {
+      return webClient.method(OPTIONS);
+    }
+
+    @BeforeTemplate
+    WebTestClient.RequestHeadersSpec<?> before(WebTestClient webClient) {
+      return webClient.method(OPTIONS);
+    }
+
+    @AfterTemplate
+    RequestHeadersSpec<?> after(WebClient webClient) {
+      return webClient.options();
+    }
+  }
+
+  /**
+   * Prefer {@link WebClient#patch()} over {@link WebClient#method(HttpMethod)} with {@link
+   * HttpMethod#PATCH}.
+   */
+  static final class WebClientPatch {
+    @BeforeTemplate
+    RequestBodyUriSpec before(WebClient webClient) {
+      return webClient.method(PATCH);
+    }
+
+    @BeforeTemplate
+    WebTestClient.RequestBodyUriSpec before(WebTestClient webClient) {
+      return webClient.method(PATCH);
+    }
+
+    @AfterTemplate
+    RequestBodyUriSpec after(WebClient webClient) {
+      return webClient.patch();
+    }
+  }
+
+  /**
+   * Prefer {@link WebClient#post()} over {@link WebClient#method(HttpMethod)} with {@link
+   * HttpMethod#POST}.
+   */
+  static final class WebClientPost {
+    @BeforeTemplate
+    RequestBodyUriSpec before(WebClient webClient) {
+      return webClient.method(POST);
+    }
+
+    @BeforeTemplate
+    WebTestClient.RequestBodyUriSpec before(WebTestClient webClient) {
+      return webClient.method(POST);
+    }
+
+    @AfterTemplate
+    RequestBodyUriSpec after(WebClient webClient) {
+      return webClient.post();
+    }
+  }
+
+  /**
+   * Prefer {@link WebClient#put()} over {@link WebClient#method(HttpMethod)} with {@link
+   * HttpMethod#PUT}.
+   */
+  static final class WebClientPut {
+    @BeforeTemplate
+    RequestBodyUriSpec before(WebClient webClient) {
+      return webClient.method(PUT);
+    }
+
+    @BeforeTemplate
+    WebTestClient.RequestBodyUriSpec before(WebTestClient webClient) {
+      return webClient.method(PUT);
+    }
+
+    @AfterTemplate
+    RequestBodyUriSpec after(WebClient webClient) {
+      return webClient.put();
+    }
+  }
+
+  /** Don't unnecessarily use {@link RequestHeadersUriSpec#uri(Function)}. */
+  abstract static class RequestHeadersUriSpecUri {
+    @BeforeTemplate
+    RequestHeadersSpec<?> before(
+        RequestHeadersUriSpec<?> requestHeadersUriSpec,
+        String path,
+        @Repeated Object uriVariables) {
+      return requestHeadersUriSpec.uri(
+          uriBuilder -> uriBuilder.path(path).build(Refaster.asVarargs(uriVariables)));
+    }
+
+    @BeforeTemplate
+    WebTestClient.RequestHeadersSpec<?> before(
+        WebTestClient.RequestHeadersUriSpec<?> requestHeadersUriSpec,
+        String path,
+        @Repeated Object uriVariables) {
+      return requestHeadersUriSpec.uri(
+          uriBuilder -> uriBuilder.path(path).build(Refaster.asVarargs(uriVariables)));
+    }
+
+    @AfterTemplate
+    RequestHeadersSpec<?> after(
+        RequestHeadersUriSpec<?> requestHeadersUriSpec,
+        String path,
+        @Repeated Object uriVariables) {
+      return requestHeadersUriSpec.uri(path, Refaster.asVarargs(uriVariables));
+    }
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/package-info.java

@@ -1,7 +1,4 @@
 /** Picnic Refaster templates. */
-@CheckReturnValue
-@ParametersAreNonnullByDefault
+@com.google.errorprone.annotations.CheckReturnValue
+@javax.annotation.ParametersAreNonnullByDefault
 package tech.picnic.errorprone.refastertemplates;
-
-import com.google.errorprone.annotations.CheckReturnValue;
-import javax.annotation.ParametersAreNonnullByDefault;

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/AmbiguousJsonCreatorTest.java

@@ -0,0 +1,148 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.common.base.Predicates.containsPattern;
+
+import com.google.errorprone.BugCheckerRefactoringTestHelper;
+import com.google.errorprone.CompilationTestHelper;
+import org.junit.jupiter.api.Test;
+
+final class AmbiguousJsonCreatorTest {
+  private final CompilationTestHelper compilationTestHelper =
+      CompilationTestHelper.newInstance(AmbiguousJsonCreator.class, getClass())
+          .expectErrorMessage(
+              "X",
+              containsPattern("`JsonCreator.Mode` should be set for single-argument creators"));
+  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
+      BugCheckerRefactoringTestHelper.newInstance(AmbiguousJsonCreator.class, getClass());
+
+  @Test
+  void identification() {
+    compilationTestHelper
+        .addSourceLines(
+            "Container.java",
+            "import com.fasterxml.jackson.annotation.JsonCreator;",
+            "import com.fasterxml.jackson.annotation.JsonValue;",
+            "",
+            "interface Container {",
+            "  enum A {",
+            "    FOO(1);",
+            "",
+            "    private final int i;",
+            "",
+            "    A(int i) {",
+            "      this.i = i;",
+            "    }",
+            "",
+            "    // BUG: Diagnostic matches: X",
+            "    @JsonCreator",
+            "    public static A of(int i) {",
+            "      return FOO;",
+            "    }",
+            "  }",
+            "",
+            "  enum B {",
+            "    FOO(1);",
+            "",
+            "    private final int i;",
+            "",
+            "    B(int i) {",
+            "      this.i = i;",
+            "    }",
+            "",
+            "    @JsonCreator(mode = JsonCreator.Mode.DELEGATING)",
+            "    public static B of(int i) {",
+            "      return FOO;",
+            "    }",
+            "  }",
+            "",
+            "  enum C {",
+            "    FOO(1, \"s\");",
+            "",
+            "    @JsonValue private final int i;",
+            "    private final String s;",
+            "",
+            "    C(int i, String s) {",
+            "      this.i = i;",
+            "      this.s = s;",
+            "    }",
+            "",
+            "    // BUG: Diagnostic matches: X",
+            "    @JsonCreator",
+            "    public static C of(int i) {",
+            "      return FOO;",
+            "    }",
+            "  }",
+            "",
+            "  enum D {",
+            "    FOO(1, \"s\");",
+            "",
+            "    private final int i;",
+            "    private final String s;",
+            "",
+            "    D(int i, String s) {",
+            "      this.i = i;",
+            "      this.s = s;",
+            "    }",
+            "",
+            "    @JsonCreator",
+            "    public static D of(int i, String s) {",
+            "      return FOO;",
+            "    }",
+            "  }",
+            "",
+            "  enum E {",
+            "    FOO;",
+            "",
+            "    // BUG: Diagnostic matches: X",
+            "    @JsonCreator",
+            "    public static E of(String s) {",
+            "      return FOO;",
+            "    }",
+            "  }",
+            "",
+            "  class F {",
+            "    private final String s;",
+            "",
+            "    F(String s) {",
+            "      this.s = s;",
+            "    }",
+            "",
+            "    @JsonCreator",
+            "    public static F of(String s) {",
+            "      return new F(s);",
+            "    }",
+            "  }",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  void replacement() {
+    refactoringTestHelper
+        .addInputLines(
+            "in/A.java",
+            "import com.fasterxml.jackson.annotation.JsonCreator;",
+            "",
+            "enum A {",
+            "  FOO;",
+            "",
+            "  @JsonCreator",
+            "  public static A of(String s) {",
+            "    return FOO;",
+            "  }",
+            "}")
+        .addOutputLines(
+            "out/A.java",
+            "import com.fasterxml.jackson.annotation.JsonCreator;",
+            "",
+            "enum A {",
+            "  FOO;",
+            "",
+            "  @JsonCreator(mode = JsonCreator.Mode.DELEGATING)",
+            "  public static A of(String s) {",
+            "    return FOO;",
+            "  }",
+            "}")
+        .doTest(BugCheckerRefactoringTestHelper.TestMode.TEXT_MATCH);
+  }
+}

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/AssertJIsNullTest.java

@@ -0,0 +1,64 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode.TEXT_MATCH;
+
+import com.google.errorprone.BugCheckerRefactoringTestHelper;
+import com.google.errorprone.CompilationTestHelper;
+import org.junit.jupiter.api.Test;
+
+final class AssertJIsNullTest {
+  private final CompilationTestHelper compilationTestHelper =
+      CompilationTestHelper.newInstance(AssertJIsNull.class, getClass());
+  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
+      BugCheckerRefactoringTestHelper.newInstance(AssertJIsNull.class, getClass());
+
+  @Test
+  void identification() {
+    compilationTestHelper
+        .addSourceLines(
+            "A.java",
+            "import static org.assertj.core.api.Assertions.assertThat;",
+            "",
+            "class A {",
+            "  void m() {",
+            "    assertThat(1).isEqualTo(1);",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(1).isEqualTo(null);",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(\"foo\").isEqualTo(null);",
+            "    isEqualTo(null);",
+            "  }",
+            "",
+            "  private boolean isEqualTo(Object value) {",
+            "    return value.equals(\"bar\");",
+            "  }",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  void replacement() {
+    refactoringTestHelper
+        .addInputLines(
+            "A.java",
+            "import static org.assertj.core.api.Assertions.assertThat;",
+            "",
+            "class A {",
+            "  void m() {",
+            "    assertThat(1).isEqualTo(null);",
+            "    assertThat(\"foo\").isEqualTo(null);",
+            "  }",
+            "}")
+        .addOutputLines(
+            "A.java",
+            "import static org.assertj.core.api.Assertions.assertThat;",
+            "",
+            "class A {",
+            "  void m() {",
+            "    assertThat(1).isNull();",
+            "    assertThat(\"foo\").isNull();",
+            "  }",
+            "}")
+        .doTest(TEXT_MATCH);
+  }
+}

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/AutowiredConstructorTest.java

@@ -5,14 +5,14 @@ import com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode;
 import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
-public final class AutowiredConstructorCheckTest {
+final class AutowiredConstructorTest {
   private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(AutowiredConstructorCheck.class, getClass());
+      CompilationTestHelper.newInstance(AutowiredConstructor.class, getClass());
   private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(new AutowiredConstructorCheck(), getClass());
+      BugCheckerRefactoringTestHelper.newInstance(AutowiredConstructor.class, getClass());
 
   @Test
-  public void testIdentification() {
+  void identification() {
     compilationTestHelper
         .addSourceLines(
             "Container.java",
@@ -27,27 +27,34 @@ public final class AutowiredConstructorCheckTest {
             "  }",
             "",
             "  class B {",
-            "    @Autowired void setProperty(Object o) {}",
+            "    @Autowired",
+            "    void setProperty(Object o) {}",
             "  }",
             "",
             "  class C {",
             "    // BUG: Diagnostic contains:",
-            "    @Autowired C() {}",
+            "    @Autowired",
+            "    C() {}",
             "  }",
             "",
             "  class D {",
             "    // BUG: Diagnostic contains:",
-            "    @Autowired D(String x) {}",
+            "    @Autowired",
+            "    D(String x) {}",
             "  }",
             "",
             "  class E {",
-            "    @Autowired E() {}",
+            "    @Autowired",
+            "    E() {}",
+            "",
             "    E(String x) {}",
             "  }",
             "",
             "  class F {",
             "    F() {}",
-            "    @Autowired F(String x) {}",
+            "",
+            "    @Autowired",
+            "    F(String x) {}",
             "  }",
             "",
             "  class G {",
@@ -55,14 +62,15 @@ public final class AutowiredConstructorCheckTest {
             "  }",
             "",
             "  class H {",
-            "    @SafeVarargs H(List<String>... lists) {}",
+            "    @SafeVarargs",
+            "    H(List<String>... lists) {}",
             "  }",
             "}")
         .doTest();
   }
 
   @Test
-  public void testReplacement() {
+  void replacement() {
     refactoringTestHelper
         .addInputLines(
             "in/Container.java",
@@ -70,11 +78,14 @@ public final class AutowiredConstructorCheckTest {
             "",
             "interface Container {",
             "  class A {",
-            "    @Autowired A() {}",
+            "    @Autowired",
+            "    @Deprecated",
+            "    A() {}",
             "  }",
             "",
             "  class B {",
-            "    @Autowired B(String x) {}",
+            "    @Autowired",
+            "    B(String x) {}",
             "  }",
             "}")
         .addOutputLines(
@@ -83,10 +94,13 @@ public final class AutowiredConstructorCheckTest {
             "",
             "interface Container {",
             "  class A {",
+            "",
+            "    @Deprecated",
             "    A() {}",
             "  }",
             "",
             "  class B {",
+            "",
             "    B(String x) {}",
             "  }",
             "}")

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/CanonicalAnnotationSyntaxCheckTest.java

@@ -1,156 +0,0 @@
-package tech.picnic.errorprone.bugpatterns;
-
-import com.google.errorprone.BugCheckerRefactoringTestHelper;
-import com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode;
-import com.google.errorprone.CompilationTestHelper;
-import org.junit.jupiter.api.Test;
-
-public final class CanonicalAnnotationSyntaxCheckTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(CanonicalAnnotationSyntaxCheck.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(new CanonicalAnnotationSyntaxCheck(), getClass());
-
-  @Test
-  public void testIdentification() {
-    compilationTestHelper
-        .addSourceLines(
-            "pkg/A.java",
-            "package pkg;",
-            "",
-            "import pkg.A.Foo;",
-            "",
-            "interface A {",
-            "  @interface Foo {",
-            "    int[] value() default {};",
-            "    int[] value2() default {};",
-            "  }",
-            "",
-            "  @pkg.A.Foo A minimal1();",
-            "  @A.Foo A minimal2();",
-            "  @Foo A minimal3();",
-            "",
-            "  // BUG: Diagnostic contains:",
-            "  @pkg.A.Foo() A functional1();",
-            "  // BUG: Diagnostic contains:",
-            "  @A.Foo() A functional2();",
-            "  // BUG: Diagnostic contains:",
-            "  @Foo() A functional3();",
-            "",
-            "  @pkg.A.Foo(1) A simple1();",
-            "  @A.Foo(1) A simple2();",
-            "  @Foo(1) A simple3();",
-            "",
-            "  // BUG: Diagnostic contains:",
-            "  @pkg.A.Foo({1}) A singleton1();",
-            "  // BUG: Diagnostic contains:",
-            "  @A.Foo({1}) A singleton2();",
-            "  // BUG: Diagnostic contains:",
-            "  @Foo({1}) A singleton3();",
-            "",
-            "  // BUG: Diagnostic contains:",
-            "  @pkg.A.Foo(value = 1) A verbose1();",
-            "  // BUG: Diagnostic contains:",
-            "  @A.Foo(value = 1) A verbose2();",
-            "  // BUG: Diagnostic contains:",
-            "  @Foo(value = 1) A verbose3();",
-            "",
-            "  @pkg.A.Foo(value2 = 2) A custom1();",
-            "  @A.Foo(value2 = 2) A custom2();",
-            "  @Foo(value2 = 2) A custom3();",
-            "",
-            "  // BUG: Diagnostic contains:",
-            "  @pkg.A.Foo(value2 = {2}) A customSingleton1();",
-            "  // BUG: Diagnostic contains:",
-            "  @A.Foo(value2 = {2}) A customSingleton2();",
-            "  // BUG: Diagnostic contains:",
-            "  @Foo(value2 = {2}) A customSingleton3();",
-            "",
-            "  @pkg.A.Foo(value2 = {2, 2}) A customPair1();",
-            "  @A.Foo(value2 = {2, 2}) A customPair2();",
-            "  @Foo(value2 = {2, 2}) A customPair3();",
-            "",
-            "  @pkg.A.Foo(value = 1, value2 = 2) A extended1();",
-            "  @A.Foo(value = 1, value2 = 2) A extended2();",
-            "  @Foo(value = 1, value2 = 2) A extended3();",
-            "",
-            "  // BUG: Diagnostic contains:",
-            "  @pkg.A.Foo({1, 1,}) A trailingComma1();",
-            "  // BUG: Diagnostic contains:",
-            "  @A.Foo({1, 1,}) A trailingComma2();",
-            "  // BUG: Diagnostic contains:",
-            "  @Foo({1, 1,}) A trailingComma3();",
-            "}")
-        .doTest();
-  }
-
-  @Test
-  public void testReplacement() {
-    refactoringTestHelper
-        .addInputLines(
-            "in/pkg/A.java",
-            "package pkg;",
-            "",
-            "import pkg.A.Foo;",
-            "",
-            "interface A {",
-            "  @interface Foo {",
-            "    String[] value() default {};",
-            "    int[] value2() default {};",
-            "  }",
-            "",
-            "  @pkg.A.Foo() A functional1();",
-            "  @A.Foo() A functional2();",
-            "  @Foo() A functional3();",
-            "",
-            "  @pkg.A.Foo(value = \"foo\") A verbose1();",
-            "  @A.Foo(value = \"a'b\") A verbose2();",
-            "  @Foo(value = \"a\" + \"\\nb\") A verbose3();",
-            "",
-            "  @pkg.A.Foo(value = {\"foo\"}) A moreVerbose1();",
-            "  @A.Foo(value = {\"a'b\"}) A moreVerbose2();",
-            "  @Foo(value = {\"a\" + \"\\nb\"}) A moreVerbose3();",
-            "",
-            "  @pkg.A.Foo(value = {\"foo\", \"bar\"}, value2 = {2}) A extended1();",
-            "  @A.Foo(value = {\"a'b\", \"c'd\"}, value2 = {2}) A extended2();",
-            "  @Foo(value = {\"a\" + \"\\nb\", \"c\" + \"\\nd\"}, value2 = {2}) A extended3();",
-            "",
-            "  @pkg.A.Foo({\"foo\", \"bar\",}) A trailingComma1();",
-            "  @A.Foo({\"a'b\", \"c'd\",}) A trailingComma2();",
-            "  @Foo({\"a\" + \"\\nb\", \"c\" + \"\\nd\",}) A trailingComma3();",
-            "}")
-        .addOutputLines(
-            "out/pkg/A.java",
-            "package pkg;",
-            "",
-            "import pkg.A.Foo;",
-            "",
-            "interface A {",
-            "  @interface Foo {",
-            "    String[] value() default {};",
-            "    int[] value2() default {};",
-            "  }",
-            "",
-            "  @pkg.A.Foo A functional1();",
-            "  @A.Foo A functional2();",
-            "  @Foo A functional3();",
-            "",
-            "  @pkg.A.Foo(\"foo\") A verbose1();",
-            "  @A.Foo(\"a'b\") A verbose2();",
-            "  @Foo(\"a\" + \"\\nb\") A verbose3();",
-            "",
-            "  @pkg.A.Foo(\"foo\") A moreVerbose1();",
-            "  @A.Foo(\"a'b\") A moreVerbose2();",
-            "  @Foo(\"a\" + \"\\nb\") A moreVerbose3();",
-            "",
-            "  @pkg.A.Foo(value = {\"foo\", \"bar\"}, value2 = 2) A extended1();",
-            "  @A.Foo(value = {\"a'b\", \"c'd\"}, value2 = 2) A extended2();",
-            "  @Foo(value = {\"a\" + \"\\nb\", \"c\" + \"\\nd\"}, value2 = 2) A extended3();",
-            "",
-            "  @pkg.A.Foo({\"foo\", \"bar\"}) A trailingComma1();",
-            "  @A.Foo({\"a'b\", \"c'd\"}) A trailingComma2();",
-            "  @Foo({\"a\" + \"\\nb\", \"c\" + \"\\nd\"}) A trailingComma3();",
-            "}")
-        .doTest(TestMode.TEXT_MATCH);
-  }
-}

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/CanonicalAnnotationSyntaxTest.java

@@ -0,0 +1,274 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import com.google.errorprone.BugCheckerRefactoringTestHelper;
+import com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode;
+import com.google.errorprone.CompilationTestHelper;
+import org.junit.jupiter.api.Test;
+
+final class CanonicalAnnotationSyntaxTest {
+  private final CompilationTestHelper compilationTestHelper =
+      CompilationTestHelper.newInstance(CanonicalAnnotationSyntax.class, getClass());
+  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
+      BugCheckerRefactoringTestHelper.newInstance(CanonicalAnnotationSyntax.class, getClass());
+
+  @Test
+  void identification() {
+    compilationTestHelper
+        .addSourceLines(
+            "pkg/A.java",
+            "package pkg;",
+            "",
+            "import pkg.A.Foo;",
+            "",
+            "interface A {",
+            "  @interface Foo {",
+            "    int[] value() default {};",
+            "",
+            "    int[] value2() default {};",
+            "  }",
+            "",
+            "  @pkg.A.Foo",
+            "  A minimal1();",
+            "",
+            "  @A.Foo",
+            "  A minimal2();",
+            "",
+            "  @Foo",
+            "  A minimal3();",
+            "",
+            "  // BUG: Diagnostic contains:",
+            "  @pkg.A.Foo()",
+            "  A functional1();",
+            "  // BUG: Diagnostic contains:",
+            "  @A.Foo()",
+            "  A functional2();",
+            "  // BUG: Diagnostic contains:",
+            "  @Foo()",
+            "  A functional3();",
+            "",
+            "  @pkg.A.Foo(1)",
+            "  A simple1();",
+            "",
+            "  @A.Foo(1)",
+            "  A simple2();",
+            "",
+            "  @Foo(1)",
+            "  A simple3();",
+            "",
+            "  // BUG: Diagnostic contains:",
+            "  @pkg.A.Foo({1})",
+            "  A singleton1();",
+            "  // BUG: Diagnostic contains:",
+            "  @A.Foo({1})",
+            "  A singleton2();",
+            "  // BUG: Diagnostic contains:",
+            "  @Foo({1})",
+            "  A singleton3();",
+            "",
+            "  // BUG: Diagnostic contains:",
+            "  @pkg.A.Foo(value = 1)",
+            "  A verbose1();",
+            "  // BUG: Diagnostic contains:",
+            "  @A.Foo(value = 1)",
+            "  A verbose2();",
+            "  // BUG: Diagnostic contains:",
+            "  @Foo(value = 1)",
+            "  A verbose3();",
+            "",
+            "  @pkg.A.Foo(value2 = 2)",
+            "  A custom1();",
+            "",
+            "  @A.Foo(value2 = 2)",
+            "  A custom2();",
+            "",
+            "  @Foo(value2 = 2)",
+            "  A custom3();",
+            "",
+            "  // BUG: Diagnostic contains:",
+            "  @pkg.A.Foo(value2 = {2})",
+            "  A customSingleton1();",
+            "  // BUG: Diagnostic contains:",
+            "  @A.Foo(value2 = {2})",
+            "  A customSingleton2();",
+            "  // BUG: Diagnostic contains:",
+            "  @Foo(value2 = {2})",
+            "  A customSingleton3();",
+            "",
+            "  @pkg.A.Foo(value2 = {2, 2})",
+            "  A customPair1();",
+            "",
+            "  @A.Foo(value2 = {2, 2})",
+            "  A customPair2();",
+            "",
+            "  @Foo(value2 = {2, 2})",
+            "  A customPair3();",
+            "",
+            "  @pkg.A.Foo(value = 1, value2 = 2)",
+            "  A extended1();",
+            "",
+            "  @A.Foo(value = 1, value2 = 2)",
+            "  A extended2();",
+            "",
+            "  @Foo(value = 1, value2 = 2)",
+            "  A extended3();",
+            "",
+            "  // BUG: Diagnostic contains:",
+            "  @pkg.A.Foo({",
+            "    1, 1,",
+            "  })",
+            "  A trailingComma1();",
+            "  // BUG: Diagnostic contains:",
+            "  @A.Foo({",
+            "    1, 1,",
+            "  })",
+            "  A trailingComma2();",
+            "  // BUG: Diagnostic contains:",
+            "  @Foo({",
+            "    1, 1,",
+            "  })",
+            "  A trailingComma3();",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  void replacement() {
+    refactoringTestHelper
+        .addInputLines(
+            "in/pkg/A.java",
+            "package pkg;",
+            "",
+            "import pkg.A.Foo;",
+            "",
+            "interface A {",
+            "  @interface Foo {",
+            "    String[] value() default {};",
+            "",
+            "    int[] value2() default {};",
+            "  }",
+            "",
+            "  @pkg.A.Foo()",
+            "  A functional1();",
+            "",
+            "  @A.Foo()",
+            "  A functional2();",
+            "",
+            "  @Foo()",
+            "  A functional3();",
+            "",
+            "  @pkg.A.Foo(value = \"foo\")",
+            "  A verbose1();",
+            "",
+            "  @A.Foo(value = \"a'b\")",
+            "  A verbose2();",
+            "",
+            "  @Foo(value = \"a\" + \"\\nb\")",
+            "  A verbose3();",
+            "",
+            "  @pkg.A.Foo(value = {\"foo\"})",
+            "  A moreVerbose1();",
+            "",
+            "  @A.Foo(value = {\"a'b\"})",
+            "  A moreVerbose2();",
+            "",
+            "  @Foo(value = {\"a\" + \"\\nb\"})",
+            "  A moreVerbose3();",
+            "",
+            "  @pkg.A.Foo(",
+            "      value = {\"foo\", \"bar\"},",
+            "      value2 = {2})",
+            "  A extended1();",
+            "",
+            "  @A.Foo(",
+            "      value = {\"a'b\", \"c'd\"},",
+            "      value2 = {2})",
+            "  A extended2();",
+            "",
+            "  @Foo(",
+            "      value = {\"a\" + \"\\nb\", \"c\" + \"\\nd\"},",
+            "      value2 = {2})",
+            "  A extended3();",
+            "",
+            "  @pkg.A.Foo({",
+            "    \"foo\", \"bar\",",
+            "  })",
+            "  A trailingComma1();",
+            "",
+            "  @A.Foo({",
+            "    \"a'b\", \"c'd\",",
+            "  })",
+            "  A trailingComma2();",
+            "",
+            "  @Foo({",
+            "    \"a\" + \"\\nb\",",
+            "    \"c\" + \"\\nd\",",
+            "  })",
+            "  A trailingComma3();",
+            "}")
+        .addOutputLines(
+            "out/pkg/A.java",
+            "package pkg;",
+            "",
+            "import pkg.A.Foo;",
+            "",
+            "interface A {",
+            "  @interface Foo {",
+            "    String[] value() default {};",
+            "",
+            "    int[] value2() default {};",
+            "  }",
+            "",
+            "  @pkg.A.Foo",
+            "  A functional1();",
+            "",
+            "  @A.Foo",
+            "  A functional2();",
+            "",
+            "  @Foo",
+            "  A functional3();",
+            "",
+            "  @pkg.A.Foo(\"foo\")",
+            "  A verbose1();",
+            "",
+            "  @A.Foo(\"a'b\")",
+            "  A verbose2();",
+            "",
+            "  @Foo(\"a\" + \"\\nb\")",
+            "  A verbose3();",
+            "",
+            "  @pkg.A.Foo(\"foo\")",
+            "  A moreVerbose1();",
+            "",
+            "  @A.Foo(\"a'b\")",
+            "  A moreVerbose2();",
+            "",
+            "  @Foo(\"a\" + \"\\nb\")",
+            "  A moreVerbose3();",
+            "",
+            "  @pkg.A.Foo(",
+            "      value = {\"foo\", \"bar\"},",
+            "      value2 = 2)",
+            "  A extended1();",
+            "",
+            "  @A.Foo(",
+            "      value = {\"a'b\", \"c'd\"},",
+            "      value2 = 2)",
+            "  A extended2();",
+            "",
+            "  @Foo(",
+            "      value = {\"a\" + \"\\nb\", \"c\" + \"\\nd\"},",
+            "      value2 = 2)",
+            "  A extended3();",
+            "",
+            "  @pkg.A.Foo({\"foo\", \"bar\"})",
+            "  A trailingComma1();",
+            "",
+            "  @A.Foo({\"a'b\", \"c'd\"})",
+            "  A trailingComma2();",
+            "",
+            "  @Foo({\"a\" + \"\\nb\", \"c\" + \"\\nd\"})",
+            "  A trailingComma3();",
+            "}")
+        .doTest(TestMode.TEXT_MATCH);
+  }
+}

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/CollectorMutabilityTest.java

@@ -0,0 +1,200 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugCheckerRefactoringTestHelper.FixChoosers.SECOND;
+
+import com.google.errorprone.BugCheckerRefactoringTestHelper;
+import com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode;
+import com.google.errorprone.CompilationTestHelper;
+import org.junit.jupiter.api.Test;
+
+final class CollectorMutabilityTest {
+  private final CompilationTestHelper compilationTestHelper =
+      CompilationTestHelper.newInstance(CollectorMutability.class, getClass());
+  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
+      BugCheckerRefactoringTestHelper.newInstance(CollectorMutability.class, getClass());
+
+  @Test
+  void identification() {
+    compilationTestHelper
+        .addSourceLines(
+            "A.java",
+            "import static com.google.common.collect.ImmutableList.toImmutableList;",
+            "import static com.google.common.collect.ImmutableMap.toImmutableMap;",
+            "import static com.google.common.collect.ImmutableSet.toImmutableSet;",
+            "import static java.util.stream.Collectors.toCollection;",
+            "import static java.util.stream.Collectors.toList;",
+            "import static java.util.stream.Collectors.toMap;",
+            "import static java.util.stream.Collectors.toSet;",
+            "",
+            "import java.util.ArrayList;",
+            "import java.util.HashMap;",
+            "import java.util.HashSet;",
+            "import java.util.stream.Collectors;",
+            "import java.util.stream.Stream;",
+            "import reactor.core.publisher.Flux;",
+            "",
+            "class A {",
+            "  void m() {",
+            "    // BUG: Diagnostic contains:",
+            "    Flux.just(1).collect(Collectors.toList());",
+            "    // BUG: Diagnostic contains:",
+            "    Flux.just(2).collect(toList());",
+            "    Flux.just(3).collect(toImmutableList());",
+            "    Flux.just(4).collect(toCollection(ArrayList::new));",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    Flux.just(\"foo\").collect(Collectors.toMap(String::getBytes, String::length));",
+            "    // BUG: Diagnostic contains:",
+            "    Flux.just(\"bar\").collect(toMap(String::getBytes, String::length));",
+            "    Flux.just(\"baz\").collect(toImmutableMap(String::getBytes, String::length));",
+            "    // BUG: Diagnostic contains:",
+            "    Flux.just(\"qux\").collect(toMap(String::getBytes, String::length, (a, b) -> a));",
+            "    Flux.just(\"quux\").collect(toImmutableMap(String::getBytes, String::length, (a, b) -> a));",
+            "    Flux.just(\"quuz\").collect(toMap(String::getBytes, String::length, (a, b) -> a, HashMap::new));",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    Stream.of(1).collect(Collectors.toSet());",
+            "    // BUG: Diagnostic contains:",
+            "    Stream.of(2).collect(toSet());",
+            "    Stream.of(3).collect(toImmutableSet());",
+            "    Stream.of(4).collect(toCollection(HashSet::new));",
+            "",
+            "    Flux.just(\"foo\").collect(Collectors.joining());",
+            "  }",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  void replacementFirstSuggestedFix() {
+    refactoringTestHelper
+        .addInputLines(
+            "A.java",
+            "import static java.util.stream.Collectors.toList;",
+            "import static java.util.stream.Collectors.toMap;",
+            "import static java.util.stream.Collectors.toSet;",
+            "",
+            "import java.util.stream.Collectors;",
+            "import java.util.stream.Stream;",
+            "import reactor.core.publisher.Flux;",
+            "",
+            "class A {",
+            "  void m() {",
+            "    Flux.just(1).collect(Collectors.toList());",
+            "    Flux.just(2).collect(toList());",
+            "",
+            "    Stream.of(\"foo\").collect(Collectors.toMap(String::getBytes, String::length));",
+            "    Stream.of(\"bar\").collect(toMap(String::getBytes, String::length));",
+            "    Flux.just(\"baz\").collect(Collectors.toMap(String::getBytes, String::length, (a, b) -> b));",
+            "    Flux.just(\"qux\").collect(toMap(String::getBytes, String::length, (a, b) -> b));",
+            "",
+            "    Stream.of(1).collect(Collectors.toSet());",
+            "    Stream.of(2).collect(toSet());",
+            "  }",
+            "}")
+        .addOutputLines(
+            "A.java",
+            "import static com.google.common.collect.ImmutableList.toImmutableList;",
+            "import static com.google.common.collect.ImmutableMap.toImmutableMap;",
+            "import static com.google.common.collect.ImmutableSet.toImmutableSet;",
+            "import static java.util.stream.Collectors.toList;",
+            "import static java.util.stream.Collectors.toMap;",
+            "import static java.util.stream.Collectors.toSet;",
+            "",
+            "import java.util.stream.Collectors;",
+            "import java.util.stream.Stream;",
+            "import reactor.core.publisher.Flux;",
+            "",
+            "class A {",
+            "  void m() {",
+            "    Flux.just(1).collect(toImmutableList());",
+            "    Flux.just(2).collect(toImmutableList());",
+            "",
+            "    Stream.of(\"foo\").collect(toImmutableMap(String::getBytes, String::length));",
+            "    Stream.of(\"bar\").collect(toImmutableMap(String::getBytes, String::length));",
+            "    Flux.just(\"baz\").collect(toImmutableMap(String::getBytes, String::length, (a, b) -> b));",
+            "    Flux.just(\"qux\").collect(toImmutableMap(String::getBytes, String::length, (a, b) -> b));",
+            "",
+            "    Stream.of(1).collect(toImmutableSet());",
+            "    Stream.of(2).collect(toImmutableSet());",
+            "  }",
+            "}")
+        .doTest(TestMode.TEXT_MATCH);
+  }
+
+  @Test
+  void replacementSecondSuggestedFix() {
+    refactoringTestHelper
+        .setFixChooser(SECOND)
+        .addInputLines(
+            "A.java",
+            "import static java.util.stream.Collectors.toList;",
+            "import static java.util.stream.Collectors.toMap;",
+            "import static java.util.stream.Collectors.toSet;",
+            "",
+            "import java.util.stream.Collectors;",
+            "import java.util.stream.Stream;",
+            "import reactor.core.publisher.Flux;",
+            "",
+            "class A {",
+            "  void m() {",
+            "    Flux.just(1).collect(Collectors.toList());",
+            "    Flux.just(2).collect(toList());",
+            "",
+            "    Stream.of(\"foo\").collect(Collectors.toMap(String::getBytes, String::length));",
+            "    Stream.of(\"bar\").collect(toMap(String::getBytes, String::length));",
+            "    Flux.just(\"baz\").collect(Collectors.toMap(String::getBytes, String::length, (a, b) -> b));",
+            "    Flux.just(\"qux\").collect(toMap(String::getBytes, String::length, (a, b) -> b));",
+            "",
+            "    Stream.of(1).collect(Collectors.toSet());",
+            "    Stream.of(2).collect(toSet());",
+            "  }",
+            "}")
+        .addOutputLines(
+            "A.java",
+            "import static java.util.stream.Collectors.toCollection;",
+            "import static java.util.stream.Collectors.toList;",
+            "import static java.util.stream.Collectors.toMap;",
+            "import static java.util.stream.Collectors.toSet;",
+            "",
+            "import java.util.ArrayList;",
+            "import java.util.HashMap;",
+            "import java.util.HashSet;",
+            "import java.util.stream.Collectors;",
+            "import java.util.stream.Stream;",
+            "import reactor.core.publisher.Flux;",
+            "",
+            "class A {",
+            "  void m() {",
+            "    Flux.just(1).collect(toCollection(ArrayList::new));",
+            "    Flux.just(2).collect(toCollection(ArrayList::new));",
+            "",
+            "    Stream.of(\"foo\")",
+            "        .collect(",
+            "            Collectors.toMap(",
+            "                String::getBytes,",
+            "                String::length,",
+            "                (a, b) -> {",
+            "                  throw new IllegalStateException();",
+            "                },",
+            "                HashMap::new));",
+            "    Stream.of(\"bar\")",
+            "        .collect(",
+            "            toMap(",
+            "                String::getBytes,",
+            "                String::length,",
+            "                (a, b) -> {",
+            "                  throw new IllegalStateException();",
+            "                },",
+            "                HashMap::new));",
+            "    Flux.just(\"baz\")",
+            "        .collect(Collectors.toMap(String::getBytes, String::length, (a, b) -> b, HashMap::new));",
+            "    Flux.just(\"qux\").collect(toMap(String::getBytes, String::length, (a, b) -> b, HashMap::new));",
+            "",
+            "    Stream.of(1).collect(toCollection(HashSet::new));",
+            "    Stream.of(2).collect(toCollection(HashSet::new));",
+            "  }",
+            "}")
+        .doTest(TestMode.TEXT_MATCH);
+  }
+}

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/EmptyMethodTest.java

@@ -5,14 +5,14 @@ import com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode;
 import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
-public final class EmptyMethodCheckTest {
+final class EmptyMethodTest {
   private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(EmptyMethodCheck.class, getClass());
+      CompilationTestHelper.newInstance(EmptyMethod.class, getClass());
   private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(new EmptyMethodCheck(), getClass());
+      BugCheckerRefactoringTestHelper.newInstance(EmptyMethod.class, getClass());
 
   @Test
-  public void testIdentification() {
+  void identification() {
     compilationTestHelper
         .addSourceLines(
             "A.java",
@@ -33,21 +33,42 @@ public final class EmptyMethodCheckTest {
             "  interface F {",
             "    void fun();",
             "  }",
+            "",
+            "  final class MyTestClass {",
+            "    void helperMethod() {}",
+            "  }",
             "}")
         .addSourceLines(
             "B.java",
+            "import org.aspectj.lang.annotation.Pointcut;",
+            "",
             "final class B implements A.F {",
             "  @Override",
             "  public void fun() {}",
             "",
             "  // BUG: Diagnostic contains:",
             "  void m3() {}",
+            "",
+            "  /** Javadoc. */",
+            "  // BUG: Diagnostic contains:",
+            "  void m4() {}",
+            "",
+            "  void m5() {",
+            "    // Single-line comment.",
+            "  }",
+            "",
+            "  void m6() {",
+            "    /* Multi-line comment. */",
+            "  }",
+            "",
+            "  @Pointcut",
+            "  void m7() {}",
             "}")
         .doTest();
   }
 
   @Test
-  public void testReplacement() {
+  void replacement() {
     refactoringTestHelper
         .addInputLines(
             "in/A.java",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/ErrorProneTestHelperSourceFormatTest.java

@@ -0,0 +1,151 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import com.google.errorprone.BugCheckerRefactoringTestHelper;
+import com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode;
+import com.google.errorprone.CompilationTestHelper;
+import org.junit.jupiter.api.Test;
+
+final class ErrorProneTestHelperSourceFormatTest {
+  private final CompilationTestHelper compilationTestHelper =
+      CompilationTestHelper.newInstance(ErrorProneTestHelperSourceFormat.class, getClass());
+  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
+      BugCheckerRefactoringTestHelper.newInstance(
+          ErrorProneTestHelperSourceFormat.class, getClass());
+
+  @Test
+  void identification() {
+    compilationTestHelper
+        .addSourceLines(
+            "A.java",
+            "import com.google.errorprone.BugCheckerRefactoringTestHelper;",
+            "import com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode;",
+            "import com.google.errorprone.CompilationTestHelper;",
+            "import tech.picnic.errorprone.bugpatterns.EmptyMethod;",
+            "",
+            "class A {",
+            "  private final CompilationTestHelper compilationTestHelper =",
+            "      CompilationTestHelper.newInstance(EmptyMethod.class, getClass());",
+            "  private final BugCheckerRefactoringTestHelper refactoringTestHelper =",
+            "      BugCheckerRefactoringTestHelper.newInstance(EmptyMethod.class, getClass());",
+            "",
+            "  void m() {",
+            "    compilationTestHelper",
+            "        // BUG: Diagnostic contains: No source code provided",
+            "        .addSourceLines(\"A.java\")",
+            "        // BUG: Diagnostic contains: Source code is malformed:",
+            "        .addSourceLines(\"B.java\", \"class B {\")",
+            "        // Well-formed code, so not flagged.",
+            "        .addSourceLines(\"C.java\", \"class C {}\")",
+            "        // Malformed code, but not compile-time constant, so not flagged.",
+            "        .addSourceLines(\"D.java\", \"class D {\" + getClass())",
+            "        // BUG: Diagnostic contains: Test code should follow the Google Java style",
+            "        .addSourceLines(\"E.java\", \"class E { }\")",
+            "        .doTest();",
+            "",
+            "    refactoringTestHelper",
+            "        // BUG: Diagnostic contains: Test code should follow the Google Java style",
+            "        .addInputLines(\"in/A.java\", \"class A { }\")",
+            "        // BUG: Diagnostic contains: Test code should follow the Google Java style",
+            "        .addOutputLines(\"out/A.java\", \"class A { }\")",
+            "        // BUG: Diagnostic contains: Test code should follow the Google Java style",
+            "        .addInputLines(\"in/B.java\", \"import java.util.Map;\", \"\", \"class B {}\")",
+            "        // Unused import, but in an output file, so not flagged.",
+            "        .addOutputLines(\"out/B.java\", \"import java.util.Map;\", \"\", \"class B {}\")",
+            "        .doTest(TestMode.TEXT_MATCH);",
+            "  }",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  void replacement() {
+    /*
+     * Verifies that import sorting and code formatting is performed unconditionally, while unused
+     * imports are removed unless part of a `BugCheckerRefactoringTestHelper` expected output file.
+     */
+    refactoringTestHelper
+        .addInputLines(
+            "in/A.java",
+            "import com.google.errorprone.BugCheckerRefactoringTestHelper;",
+            "import com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode;",
+            "import com.google.errorprone.CompilationTestHelper;",
+            "import tech.picnic.errorprone.bugpatterns.EmptyMethod;",
+            "",
+            "class A {",
+            "  private final CompilationTestHelper compilationTestHelper =",
+            "      CompilationTestHelper.newInstance(EmptyMethod.class, getClass());",
+            "  private final BugCheckerRefactoringTestHelper refactoringTestHelper =",
+            "      BugCheckerRefactoringTestHelper.newInstance(EmptyMethod.class, getClass());",
+            "",
+            "  void m() {",
+            "    compilationTestHelper",
+            "        .addSourceLines(",
+            "            \"A.java\",",
+            "            \"import java.util.Map;\",",
+            "            \"import java.util.Collection;\",",
+            "            \"import java.util.List;\",",
+            "            \"\",",
+            "            \"interface A extends List<A>, Map<A,A> { }\")",
+            "        .doTest();",
+            "",
+            "    refactoringTestHelper",
+            "        .addInputLines(",
+            "            \"in/A.java\",",
+            "            \"import java.util.Map;\",",
+            "            \"import java.util.Collection;\",",
+            "            \"import java.util.List;\",",
+            "            \"\",",
+            "            \"interface A extends List<A>, Map<A,A> { }\")",
+            "        .addOutputLines(",
+            "            \"out/A.java\",",
+            "            \"import java.util.Map;\",",
+            "            \"import java.util.Collection;\",",
+            "            \"import java.util.List;\",",
+            "            \"\",",
+            "            \"interface A extends List<A>, Map<A,A> { }\")",
+            "        .doTest(TestMode.TEXT_MATCH);",
+            "  }",
+            "}")
+        .addOutputLines(
+            "out/A.java",
+            "import com.google.errorprone.BugCheckerRefactoringTestHelper;",
+            "import com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode;",
+            "import com.google.errorprone.CompilationTestHelper;",
+            "import tech.picnic.errorprone.bugpatterns.EmptyMethod;",
+            "",
+            "class A {",
+            "  private final CompilationTestHelper compilationTestHelper =",
+            "      CompilationTestHelper.newInstance(EmptyMethod.class, getClass());",
+            "  private final BugCheckerRefactoringTestHelper refactoringTestHelper =",
+            "      BugCheckerRefactoringTestHelper.newInstance(EmptyMethod.class, getClass());",
+            "",
+            "  void m() {",
+            "    compilationTestHelper",
+            "        .addSourceLines(",
+            "            \"A.java\",",
+            "            \"import java.util.List;\",",
+            "            \"import java.util.Map;\",",
+            "            \"\",",
+            "            \"interface A extends List<A>, Map<A, A> {}\")",
+            "        .doTest();",
+            "",
+            "    refactoringTestHelper",
+            "        .addInputLines(",
+            "            \"in/A.java\",",
+            "            \"import java.util.List;\",",
+            "            \"import java.util.Map;\",",
+            "            \"\",",
+            "            \"interface A extends List<A>, Map<A, A> {}\")",
+            "        .addOutputLines(",
+            "            \"out/A.java\",",
+            "            \"import java.util.Collection;\",",
+            "            \"import java.util.List;\",",
+            "            \"import java.util.Map;\",",
+            "            \"\",",
+            "            \"interface A extends List<A>, Map<A, A> {}\")",
+            "        .doTest(TestMode.TEXT_MATCH);",
+            "  }",
+            "}")
+        .doTest(TestMode.TEXT_MATCH);
+  }
+}