FAILED experiment

I sense that we can do better, but it won't be trivial.

.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".

.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

@@ -1,37 +0,0 @@
----
-dist: bionic
-language: java
-jdk: openjdk11
-addons:
-  sonarcloud:
-    organization: picnic-technologies
-    token: "${SONARCLOUD_TOKEN}"
-install:
-  - mvn io.takari:maven:wrapper
-script:
-  # We run the build twice: once against the original Error Prone release,
-  # using only Error Prone checks available on Maven Central, and once against
-  # the Picnic Error Prone fork, additionally enabling Error Prone checks
-  # available from other artifact repositories.
-  - ./mvnw clean install
-  - ./mvnw clean install -Perror-prone-fork -Pnon-maven-central -s settings.xml
-  # XXX: Enable SonarCloud once we "go public".
-  # ./mvnw jacoco:prepare-agent surefire:test jacoco:report sonar:sonar
-  - ./mvnw jacoco:prepare-agent surefire:test jacoco:report
-before_cache:
-  # Don't cache the artifacts we just generated, for multiple reasons: (1) we
-  # shouldn't need them next time around and (2) if we do, that indicates a
-  # dependency issue which might otherwise go unnoticed until next time we bump
-  # the project's version (i.e., when tagging).
-  - find "${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

@@ -276,10 +276,6 @@ Refaster's expressiveness:
   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.)
-- Upon application of a template Refaster can throw a _No binding for
-  Key{identifier=someAfterTemplateParam}_ exception. When this happens the
-  template is invalid. Instead perform this check at compile time, such that
-  such malformed templates cannot be defined in the first place.
 - 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

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>
@@ -112,6 +128,11 @@
             <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>
@@ -123,8 +144,8 @@
             <scope>provided</scope>
         </dependency>
         <dependency>
-            <groupId>org.hamcrest</groupId>
-            <artifactId>hamcrest-library</artifactId>
+            <groupId>org.immutables</groupId>
+            <artifactId>value-annotations</artifactId>
             <scope>test</scope>
         </dependency>
         <dependency>
@@ -159,18 +180,23 @@
         </dependency>
         <dependency>
             <groupId>org.springframework</groupId>
-            <artifactId>spring-beans</artifactId>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.springframework</groupId>
-            <artifactId>spring-context</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>
@@ -182,15 +208,6 @@
     <build>
         <pluginManagement>
             <plugins>
-                <plugin>
-                    <groupId>com.coveo</groupId>
-                    <artifactId>fmt-maven-plugin</artifactId>
-                    <configuration>
-                        <additionalSourceDirectories>
-                            <additionalSourceDirectory>${basedir}/src/test/resources</additionalSourceDirectory>
-                        </additionalSourceDirectories>
-                    </configuration>
-                </plugin>
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-compiler-plugin</artifactId>
@@ -198,15 +215,31 @@
                         <annotationProcessorPaths combine.children="append">
                             <path>
                                 <groupId>${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

@@ -1,15 +1,16 @@
 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.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.ClassTreeMatcher;
@@ -26,12 +27,11 @@ import java.util.List;
 /** 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)
-public final class AutowiredConstructorCheck extends BugChecker implements ClassTreeMatcher {
+    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"));
@@ -43,7 +43,7 @@ public final class AutowiredConstructorCheck extends BugChecker implements Class
       return Description.NO_MATCH;
     }
 
-    List<AnnotationTree> annotations =
+    ImmutableList<AnnotationTree> annotations =
         AUTOWIRED_ANNOTATION
             .multiMatchResult(Iterables.getOnlyElement(constructors), state)
             .matchingNodes();

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

@@ -1,11 +1,12 @@
 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.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;
@@ -24,25 +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)
-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) {
@@ -102,7 +102,8 @@ public final class CanonicalAnnotationSyntaxCheck extends BugChecker
     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) {
@@ -137,11 +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

@@ -1,5 +1,8 @@
 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;
@@ -7,9 +10,6 @@ import static com.google.errorprone.matchers.Matchers.isType;
 
 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;
@@ -17,21 +17,21 @@ 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 com.sun.tools.javac.code.Symbol.MethodSymbol;
+import java.util.Optional;
 
 /** 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.SUGGESTION,
-    tags = StandardTags.SIMPLIFICATION)
-public final class EmptyMethodCheck extends BugChecker implements MethodTreeMatcher {
+    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> HAS_PERMITTED_ANNOTATION =
+  private static final Matcher<Tree> PERMITTED_ANNOTATION =
       annotations(
           AT_LEAST_ONE,
           anyOf(isType("java.lang.Override"), isType("org.aspectj.lang.annotation.Pointcut")));
@@ -41,15 +41,22 @@ public final class EmptyMethodCheck extends BugChecker implements MethodTreeMatc
     if (tree.getBody() == null
         || !tree.getBody().getStatements().isEmpty()
         || ASTHelpers.containsComments(tree, state)
-        || HAS_PERMITTED_ANNOTATION.matches(tree, state)) {
+        || PERMITTED_ANNOTATION.matches(tree, state)
+        || isInPossibleTestHelperClass(state)) {
       return Description.NO_MATCH;
     }
 
-    MethodSymbol sym = ASTHelpers.getSymbol(tree);
-    if (sym == null || ASTHelpers.methodCanBeOverridden(sym)) {
+    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/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/JUnitMethodDeclarationCheck.java

@@ -1,114 +0,0 @@
-package tech.picnic.errorprone.bugpatterns;
-
-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 static java.util.function.Predicate.not;
-
-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.MultiMatcher;
-import com.google.errorprone.predicates.TypePredicate;
-import com.google.errorprone.util.ASTHelpers;
-import com.sun.source.tree.AnnotationTree;
-import com.sun.source.tree.MethodTree;
-import com.sun.tools.javac.code.Symbol;
-import java.util.Optional;
-import javax.lang.model.element.Modifier;
-
-/** 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`, 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(
-    name = "JUnitMethodDeclaration",
-    summary = "JUnit method declaration can likely be improved",
-    linkType = BugPattern.LinkType.NONE,
-    severity = BugPattern.SeverityLevel.SUGGESTION,
-    tags = BugPattern.StandardTags.SIMPLIFICATION)
-public final class JUnitMethodDeclarationCheck 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 MultiMatcher<MethodTree, AnnotationTree> IS_OVERRIDE_METHOD =
-      annotations(AT_LEAST_ONE, isType("java.lang.Override"));
-  private static final MultiMatcher<MethodTree, AnnotationTree> IS_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> IS_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) {
-    // XXX: Perhaps we should also skip analysis of non-`private` non-`final` methods in abstract
-    // classes?
-    if (IS_OVERRIDE_METHOD.matches(tree, state)) {
-      return Description.NO_MATCH;
-    }
-
-    boolean isTestMethod = IS_TEST_METHOD.matches(tree, state);
-    if (!isTestMethod && !IS_SETUP_OR_TEARDOWN_METHOD.matches(tree, state)) {
-      return Description.NO_MATCH;
-    }
-
-    SuggestedFix.Builder builder = SuggestedFix.builder();
-    SuggestedFixes.removeModifiers(tree.getModifiers(), state, ILLEGAL_MODIFIERS)
-        .ifPresent(builder::merge);
-
-    if (isTestMethod) {
-      // XXX: In theory this rename could clash with an existing method or static import. In that
-      // case we should emit a warning without a suggested replacement.
-      tryCanonicalizeMethodName(tree, state).ifPresent(builder::merge);
-    }
-
-    return builder.isEmpty() ? Description.NO_MATCH : describeMatch(tree, builder.build());
-  }
-
-  private static Optional<SuggestedFix> tryCanonicalizeMethodName(
-      MethodTree tree, VisitorState state) {
-    return Optional.ofNullable(ASTHelpers.getSymbol(tree))
-        .map(sym -> sym.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)))
-        .map(name -> SuggestedFixes.renameMethod(tree, name, state));
-  }
-
-  // XXX: Move to a `MoreMatchers` utility class.
-  private static Matcher<AnnotationTree> hasMetaAnnotation(String annotationClassName) {
-    TypePredicate typePredicate = hasAnnotation(annotationClassName);
-    return (tree, state) -> {
-      Symbol sym = ASTHelpers.getDeclaredSymbol(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 +1,9 @@
 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;
 
@@ -8,9 +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.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.
@@ -46,12 +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)
-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 +62,27 @@ public final class LexicographicalAnnotationAttributeListingCheck extends BugChe
           "com.fasterxml.jackson.annotation.JsonPropertyOrder#value",
           "io.swagger.annotations.ApiImplicitParams#value",
           "io.swagger.v3.oas.annotations.Parameters#value",
-          "javax.xml.bind.annotation.XmlType#propOrder");
+          "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));
   }
@@ -153,7 +158,7 @@ public final class LexicographicalAnnotationAttributeListingCheck extends BugChe
     // 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(
@@ -171,20 +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);
       }
@@ -194,7 +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

@@ -1,14 +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.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;
@@ -47,15 +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)
-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
@@ -67,7 +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);
   }
@@ -97,6 +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)
@@ -153,6 +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.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;
@@ -30,6 +30,8 @@ import com.sun.tools.javac.tree.JCTree.JCMemberReference;
 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
@@ -37,18 +39,15 @@ import java.util.function.Function;
  */
 // XXX: Add more documentation. Explain how this is useful in the face of refactoring to more
 // specific types.
-// XXX: Change this checker's name?
 @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)
-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_COMPARISON_METHOD =
       anyOf(
@@ -77,23 +76,52 @@ public final class PrimitiveComparisonCheck extends BugChecker
     }
 
     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();
 
@@ -128,9 +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();
@@ -143,7 +168,7 @@ 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());
     }

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;
@@ -12,9 +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.SeverityLevel;
-import com.google.errorprone.BugPattern.StandardTags;
 import com.google.errorprone.ErrorProneFlags;
 import com.google.errorprone.VisitorState;
 import com.google.errorprone.bugpatterns.BugChecker;
@@ -41,16 +41,17 @@ import java.util.List;
 import java.util.Locale;
 import java.util.Objects;
 import java.util.Optional;
+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)
-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:";
@@ -64,7 +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 =
@@ -156,17 +158,17 @@ public final class RedundantStringConversionCheck extends BugChecker
 
   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);
   }
 
@@ -325,7 +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(
@@ -349,7 +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));
     }
   }
 
@@ -362,7 +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

@@ -1,21 +1,19 @@
 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.isSubtypeOf;
 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.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.MethodTreeMatcher;
@@ -32,13 +30,11 @@ import com.sun.source.tree.Tree;
  */
 @AutoService(BugChecker.class)
 @BugPattern(
-    name = "RequestMappingAnnotation",
     summary = "Make sure all `@RequestMapping` method parameters are annotated",
-    linkType = LinkType.NONE,
-    severity = SeverityLevel.WARNING,
-    tags = StandardTags.LIKELY_ERROR,
-    providesFix = ProvidesFix.REQUIRES_HUMAN_ATTENTION)
-public final class RequestMappingAnnotationCheck extends BugChecker implements MethodTreeMatcher {
+    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
@@ -53,8 +49,11 @@ public final class RequestMappingAnnotationCheck extends BugChecker implements M
               isType(ANN_PACKAGE_PREFIX + "PostMapping"),
               isType(ANN_PACKAGE_PREFIX + "PutMapping"),
               isType(ANN_PACKAGE_PREFIX + "RequestMapping")));
-  // XXX: Add other parameters as necessary. See
-  // https://docs.spring.io/spring/docs/current/spring-framework-reference/web.html#mvc-ann-arguments.
+  // 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(
@@ -64,14 +63,22 @@ public final class RequestMappingAnnotationCheck extends BugChecker implements M
                       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"),
-                  isSubtypeOf("org.springframework.web.context.request.WebRequest"))));
+                  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) {

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

@@ -1,15 +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.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;
@@ -22,6 +22,7 @@ import com.sun.source.tree.MethodInvocationTree;
 import com.sun.source.tree.Tree.Kind;
 import java.util.List;
 import java.util.Optional;
+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
@@ -31,13 +32,11 @@ import java.util.Optional;
 // 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)
-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);
@@ -114,7 +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 +1,9 @@
 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;
 
@@ -9,9 +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.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
@@ -32,13 +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)
-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 =
@@ -92,7 +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:
@@ -105,7 +106,7 @@ public final class SpringMvcAnnotationCheck extends BugChecker implements Annota
     String newArguments =
         tree.getArguments().stream()
             .filter(not(argToRemove::equals))
-            .map(arg -> Util.treeToString(arg, state))
+            .map(arg -> SourceCode.treeToString(arg, state))
             .collect(joining(", "));
 
     return SuggestedFix.builder()

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

@@ -1,13 +1,15 @@
 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.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.MemberSelectTreeMatcher;
@@ -17,15 +19,18 @@ 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 java.util.Objects;
+import com.sun.tools.javac.code.Type;
 import java.util.Optional;
 
-/** A {@link BugChecker} which flags methods that can and should be statically imported. */
+/**
+ * A {@link BugChecker} which flags methods and constants that can and should be statically
+ * imported.
+ */
 // XXX: Tricky cases:
-// - `org.springframework.http.MediaType` (do except for `ALL`?)
 // - `org.springframework.http.HttpStatus` (not always an improvement, and `valueOf` must
 //    certainly be excluded)
 // - `com.google.common.collect.Tables`
@@ -40,21 +45,29 @@ import java.util.Optional;
 // - Likely any of `*.{ZERO, ONE, MIX, MAX, MIN_VALUE, MAX_VALUE}`.
 @AutoService(BugChecker.class)
 @BugPattern(
-    name = "StaticImport",
-    summary = "Method should be statically imported",
-    linkType = LinkType.NONE,
-    severity = SeverityLevel.SUGGESTION,
-    tags = StandardTags.SIMPLIFICATION)
-public final class StaticImportCheck extends BugChecker implements MemberSelectTreeMatcher {
+    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_CLASSES =
+  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",
@@ -63,8 +76,10 @@ public final class StaticImportCheck extends BugChecker implements MemberSelectT
           "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",
@@ -79,14 +94,17 @@ public final class StaticImportCheck extends BugChecker implements MemberSelectT
           "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_METHODS =
+  static final ImmutableSetMultimap<String, String> STATIC_IMPORT_CANDIDATE_MEMBERS =
       ImmutableSetMultimap.<String, String>builder()
           .putAll(
               "com.google.common.collect.ImmutableListMultimap",
@@ -107,8 +125,10 @@ public final class StaticImportCheck extends BugChecker implements MemberSelectT
           .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",
@@ -121,9 +141,57 @@ public final class StaticImportCheck extends BugChecker implements MemberSelectT
           .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 (!isCandidate(state)) {
+    if (!isCandidateContext(state) || !isCandidate(tree)) {
       return Description.NO_MATCH;
     }
 
@@ -138,10 +206,9 @@ public final class StaticImportCheck extends BugChecker implements MemberSelectT
         .orElse(Description.NO_MATCH);
   }
 
-  private static boolean isCandidate(VisitorState state) {
+  private static boolean isCandidateContext(VisitorState state) {
     Tree parentTree =
-        Objects.requireNonNull(
-                state.getPath().getParentPath(), "MemberSelectTree lacks enclosing node")
+        requireNonNull(state.getPath().getParentPath(), "MemberSelectTree lacks enclosing node")
             .getLeaf();
     switch (parentTree.getKind()) {
       case IMPORT:
@@ -154,6 +221,17 @@ public final class StaticImportCheck extends BugChecker implements MemberSelectT
     }
   }
 
+  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
@@ -161,8 +239,8 @@ public final class StaticImportCheck extends BugChecker implements MemberSelectT
         .toJavaUtil()
         .filter(
             name ->
-                STATIC_IMPORT_CANDIDATE_CLASSES.contains(canonicalName)
-                    || STATIC_IMPORT_CANDIDATE_METHODS.containsEntry(canonicalName, name));
+                STATIC_IMPORT_CANDIDATE_TYPES.contains(canonicalName)
+                    || STATIC_IMPORT_CANDIDATE_MEMBERS.containsEntry(canonicalName, name));
   }
 
   private static Optional<Fix> tryStaticImport(

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;
@@ -28,7 +28,7 @@ import java.util.stream.Stream;
  * <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;
@@ -59,7 +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<>();
@@ -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

@@ -1,8 +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 AssertJObjectTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ObjectAssert<S> after(S object) {
       return assertThat(object).isInstanceOf(Refaster.<T>clazz());
     }
@@ -34,7 +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());
     }
@@ -47,7 +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);
     }
@@ -60,7 +60,7 @@ 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);
     }
@@ -73,7 +73,7 @@ final class AssertJObjectTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @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;
@@ -26,7 +26,7 @@ final class AssertJOptionalTemplates {
     }
 
     @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();
     }
@@ -97,12 +97,24 @@ final class AssertJOptionalTemplates {
     }
 
     @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) {
@@ -110,7 +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
@@ -94,7 +97,6 @@ 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
@@ -134,7 +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);
     }
@@ -153,7 +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);
     }
@@ -172,7 +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);
     }
@@ -338,8 +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
@@ -349,16 +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
     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
@@ -371,13 +391,12 @@ final class AssertJTemplates {
   static final class ObjectEnumerableIsSubsetOfOneElement<S, T extends S> {
     @BeforeTemplate
     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
@@ -395,8 +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());
     }
@@ -405,13 +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();
     }
@@ -435,7 +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();
     }
@@ -453,7 +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);
     }
@@ -466,7 +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);
     }
@@ -483,7 +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);
     }
@@ -500,7 +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);
     }
@@ -512,15 +530,15 @@ 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);
     }
   }
@@ -531,13 +549,13 @@ final class AssertJTemplates {
 
   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);
     }
   }
@@ -602,8 +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());
     }
@@ -614,7 +632,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Map<K, V> map) {
       assertThat(map).isEmpty();
     }
@@ -651,7 +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();
     }
@@ -666,7 +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);
     }
@@ -680,7 +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);
     }
@@ -694,7 +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);
     }
@@ -707,7 +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);
     }
@@ -720,7 +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);
     }
@@ -745,7 +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);
     }
@@ -766,7 +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);
     }
@@ -775,19 +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);
     }
@@ -808,7 +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);
     }
@@ -829,7 +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);
     }
@@ -838,19 +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);
     }
@@ -865,7 +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);
     }
@@ -880,7 +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);
     }
@@ -889,13 +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);
     }
@@ -911,13 +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);
     }
@@ -932,13 +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);
     }
@@ -947,6 +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))
@@ -954,14 +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);
     }
@@ -982,7 +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);
     }
@@ -991,13 +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);
     }
@@ -1018,7 +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);
     }
@@ -1027,6 +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))
@@ -1034,7 +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);
     }
@@ -1055,7 +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);
     }
@@ -1076,7 +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);
     }
@@ -1085,19 +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);
     }
@@ -1118,7 +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);
     }
@@ -1127,6 +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))
@@ -1134,7 +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);
     }
@@ -1155,7 +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);
     }
@@ -1176,7 +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);
     }
@@ -1185,19 +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);
     }
@@ -1230,7 +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);
     }
@@ -1239,19 +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);
     }
@@ -1270,7 +1309,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Stream<S> stream) {
       assertThat(stream).isEmpty();
     }
@@ -1289,7 +1328,7 @@ final class AssertJTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after(Stream<S> stream) {
       assertThat(stream).isNotEmpty();
     }
@@ -1302,7 +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);
     }
@@ -1319,7 +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);
     }
@@ -1332,7 +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);
     }
@@ -2173,7 +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

@@ -1,16 +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;
@@ -38,12 +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);
     }
   }
 
@@ -62,14 +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);
     }
@@ -91,7 +93,7 @@ final class AssortedTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     ImmutableSet<T> after(Stream<T> stream) {
       return stream.collect(toImmutableEnumSet());
     }
@@ -107,8 +109,8 @@ final class AssortedTemplates {
           Streams.stream(iterator).findAny().orElse(defaultValue));
     }
 
-    @Nullable
     @AfterTemplate
+    @Nullable
     T after(Iterator<T> iterator, T defaultValue) {
       return Iterators.getNext(iterator, defaultValue);
     }
@@ -161,7 +163,7 @@ final class AssortedTemplates {
 
     @AfterTemplate
     boolean after(Set<T> set1, Set<T> set2) {
-      return Collections.disjoint(set1, set2);
+      return disjoint(set1, set2);
     }
   }
 
@@ -176,15 +178,15 @@ final class AssortedTemplates {
     @BeforeTemplate
     boolean before(Collection<T> collection1, Collection<T> collection2) {
       return Refaster.anyOf(
-          Collections.disjoint(ImmutableSet.copyOf(collection1), collection2),
-          Collections.disjoint(new HashSet<>(collection1), collection2),
-          Collections.disjoint(collection1, ImmutableSet.copyOf(collection2)),
-          Collections.disjoint(collection1, new HashSet<>(collection2)));
+          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 Collections.disjoint(collection1, collection2);
+      return disjoint(collection1, collection2);
     }
   }
 
@@ -256,11 +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

@@ -15,6 +15,7 @@ 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;
@@ -129,31 +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);
     }
   }
 
@@ -187,7 +189,7 @@ final class CollectionTemplates {
    * Don't call {@link ImmutableCollection#asList()} if the result is going to be streamed; stream
    * directly.
    */
-  static final class ImmutableCollectionAsListToStream<T> {
+  static final class ImmutableCollectionStream<T> {
     @BeforeTemplate
     Stream<T> before(ImmutableCollection<T> collection) {
       return collection.asList().stream();

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

@@ -1,12 +1,17 @@
 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.common.collect.Comparators;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
-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;
@@ -29,14 +34,13 @@ final class ComparatorTemplates {
     @BeforeTemplate
     Comparator<T> before() {
       return Refaster.anyOf(
-          Comparator.comparing(Refaster.anyOf(identity(), v -> v)),
-          Comparator.<T>reverseOrder().reversed());
+          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();
+      return naturalOrder();
     }
   }
 
@@ -48,7 +52,7 @@ final class ComparatorTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     Comparator<T> after() {
       return reverseOrder();
     }
@@ -58,11 +62,11 @@ final class ComparatorTemplates {
     // XXX: Drop the `Refaster.anyOf` if/when we decide to rewrite one to the other.
     @BeforeTemplate
     Comparator<T> before(Comparator<T> cmp) {
-      return Comparator.comparing(Refaster.anyOf(identity(), v -> v), cmp);
+      return comparing(Refaster.anyOf(identity(), v -> v), cmp);
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     Comparator<T> after(Comparator<T> cmp) {
       return cmp;
     }
@@ -72,7 +76,7 @@ final class ComparatorTemplates {
   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(Comparator.comparing(function));
+      return cmp.thenComparing(comparing(function));
     }
 
     @AfterTemplate
@@ -85,11 +89,11 @@ final class ComparatorTemplates {
   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(Comparator.comparing(function).reversed());
+      return cmp.thenComparing(comparing(function).reversed());
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     Comparator<S> after(Comparator<S> cmp, Function<? super S, ? extends T> function) {
       return cmp.thenComparing(function, reverseOrder());
     }
@@ -100,7 +104,7 @@ final class ComparatorTemplates {
     @BeforeTemplate
     Comparator<S> before(
         Comparator<S> cmp, Function<? super S, ? extends T> function, Comparator<? super T> cmp2) {
-      return cmp.thenComparing(Comparator.comparing(function, cmp2));
+      return cmp.thenComparing(comparing(function, cmp2));
     }
 
     @AfterTemplate
@@ -115,7 +119,7 @@ final class ComparatorTemplates {
     @BeforeTemplate
     Comparator<S> before(
         Comparator<S> cmp, Function<? super S, ? extends T> function, Comparator<? super T> cmp2) {
-      return cmp.thenComparing(Comparator.comparing(function, cmp2).reversed());
+      return cmp.thenComparing(comparing(function, cmp2).reversed());
     }
 
     @AfterTemplate
@@ -129,7 +133,7 @@ final class ComparatorTemplates {
   static final class ThenComparingDouble<T> {
     @BeforeTemplate
     Comparator<T> before(Comparator<T> cmp, ToDoubleFunction<? super T> function) {
-      return cmp.thenComparing(Comparator.comparingDouble(function));
+      return cmp.thenComparing(comparingDouble(function));
     }
 
     @AfterTemplate
@@ -142,7 +146,7 @@ final class ComparatorTemplates {
   static final class ThenComparingInt<T> {
     @BeforeTemplate
     Comparator<T> before(Comparator<T> cmp, ToIntFunction<? super T> function) {
-      return cmp.thenComparing(Comparator.comparingInt(function));
+      return cmp.thenComparing(comparingInt(function));
     }
 
     @AfterTemplate
@@ -155,7 +159,7 @@ final class ComparatorTemplates {
   static final class ThenComparingLong<T> {
     @BeforeTemplate
     Comparator<T> before(Comparator<T> cmp, ToLongFunction<? super T> function) {
-      return cmp.thenComparing(Comparator.comparingLong(function));
+      return cmp.thenComparing(comparingLong(function));
     }
 
     @AfterTemplate
@@ -176,9 +180,9 @@ final class ComparatorTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     Comparator<T> after(Comparator<T> cmp) {
-      return cmp.thenComparing(Comparator.naturalOrder());
+      return cmp.thenComparing(naturalOrder());
     }
   }
 

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

@@ -233,10 +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
@@ -251,10 +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;
@@ -41,37 +40,6 @@ 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.
    */
@@ -108,40 +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
@@ -195,9 +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;
@@ -90,29 +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;
@@ -39,37 +37,6 @@ 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> {
     @BeforeTemplate
@@ -105,41 +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
@@ -152,4 +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/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;
@@ -93,14 +90,14 @@ final class ImmutableSortedMultisetTemplates {
   // `reverseOrder`.) Worth the hassle?
   static final class IterableToImmutableSortedMultiset<T extends Comparable<? super T>> {
     @BeforeTemplate
-    ImmutableMultiset<T> before(T[] iterable) {
+    ImmutableSortedMultiset<T> before(T[] iterable) {
       return Refaster.anyOf(
           ImmutableSortedMultiset.<T>naturalOrder().add(iterable).build(),
           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(),
@@ -108,7 +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(),
@@ -134,14 +131,11 @@ final class ImmutableSortedMultisetTemplates {
   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;
@@ -91,14 +88,14 @@ final class ImmutableSortedSetTemplates {
   // `reverseOrder`.) Worth the hassle?
   static final class IterableToImmutableSortedSet<T extends Comparable<? super T>> {
     @BeforeTemplate
-    ImmutableSet<T> before(T[] iterable) {
+    ImmutableSortedSet<T> before(T[] iterable) {
       return Refaster.anyOf(
           ImmutableSortedSet.<T>naturalOrder().add(iterable).build(),
           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(),
@@ -106,7 +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(),
@@ -134,14 +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

@@ -246,10 +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
@@ -264,10 +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

@@ -1,8 +1,8 @@
 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.ImportPolicy;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import com.google.errorprone.refaster.annotation.Repeated;
@@ -21,7 +21,7 @@ final class JUnitTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     Arguments after(@Repeated T objects) {
       return arguments(objects);
     }

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

@@ -246,10 +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
@@ -264,10 +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

@@ -1,10 +1,10 @@
 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.ImportPolicy;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import com.google.errorprone.refaster.annotation.UseImportPolicy;
@@ -26,7 +26,7 @@ final class MockitoTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     VerificationMode after() {
       return never();
     }
@@ -43,7 +43,7 @@ final class MockitoTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @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);
     }
 
@@ -91,19 +93,6 @@ final class OptionalTemplates {
     }
   }
 
-  /** Prefer {@link Optional#stream()} over the Guava alternative. */
-  static final class OptionalToStream<T> {
-    @BeforeTemplate
-    Stream<T> before(Optional<T> optional) {
-      return Streams.stream(optional);
-    }
-
-    @AfterTemplate
-    Stream<T> after(Optional<T> optional) {
-      return optional.stream();
-    }
-  }
-
   /**
    * Don't use the ternary operator to extract the first element of a possibly-empty {@link
    * Iterator} as an {@link Optional}.
@@ -115,7 +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();
     }
@@ -124,7 +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);
@@ -144,7 +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);
@@ -177,6 +166,11 @@ 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);
@@ -245,9 +239,16 @@ 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);
@@ -317,6 +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

@@ -1,9 +1,10 @@
 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.ImportPolicy;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
@@ -77,7 +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
@@ -94,7 +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
@@ -142,6 +143,35 @@ final class ReactorTemplates {
     }
   }
 
+  /** 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}.
@@ -161,6 +191,19 @@ final class ReactorTemplates {
     }
   }
 
+  /** 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.
    */
@@ -175,12 +218,38 @@ final class ReactorTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @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
@@ -194,6 +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
@@ -252,7 +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

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

@@ -1,11 +1,12 @@
 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.ImportPolicy;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
@@ -18,12 +19,31 @@ 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
@@ -148,6 +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) {
@@ -214,7 +236,7 @@ final class StreamTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     Optional<T> after(Stream<T> stream) {
       return stream.min(naturalOrder());
     }
@@ -240,7 +262,7 @@ final class StreamTemplates {
     }
 
     @AfterTemplate
-    @UseImportPolicy(ImportPolicy.STATIC_IMPORT_ALWAYS)
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     Optional<T> after(Stream<T> stream) {
       return stream.max(naturalOrder());
     }
@@ -294,10 +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
@@ -312,10 +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

@@ -1,5 +1,6 @@
 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;
@@ -10,10 +11,10 @@ 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 java.nio.charset.StandardCharsets;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Optional;
+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)`?
@@ -37,7 +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();
     }
 
@@ -122,7 +123,7 @@ final class StringTemplates {
   static final class Utf8EncodedLength {
     @BeforeTemplate
     int before(String str) {
-      return str.getBytes(StandardCharsets.UTF_8).length;
+      return str.getBytes(UTF_8).length;
     }
 
     @AfterTemplate

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;
@@ -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 @Deprecated 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() {}",
+            "",
+            "    @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",
@@ -33,6 +33,10 @@ public final class EmptyMethodCheckTest {
             "  interface F {",
             "    void fun();",
             "  }",
+            "",
+            "  final class MyTestClass {",
+            "    void helperMethod() {}",
+            "  }",
             "}")
         .addSourceLines(
             "B.java",
@@ -64,7 +68,7 @@ public final class EmptyMethodCheckTest {
   }
 
   @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);
+  }
+}

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

@@ -0,0 +1,85 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import com.google.errorprone.CompilationTestHelper;
+import org.junit.jupiter.api.Test;
+
+final class ExplicitEnumOrderingTest {
+  private final CompilationTestHelper compilationTestHelper =
+      CompilationTestHelper.newInstance(ExplicitEnumOrdering.class, getClass());
+
+  @Test
+  void identification() {
+    compilationTestHelper
+        .addSourceLines(
+            "A.java",
+            "import static java.lang.annotation.RetentionPolicy.CLASS;",
+            "import static java.lang.annotation.RetentionPolicy.RUNTIME;",
+            "import static java.lang.annotation.RetentionPolicy.SOURCE;",
+            "import static java.time.chrono.IsoEra.BCE;",
+            "import static java.time.chrono.IsoEra.CE;",
+            "",
+            "import com.google.common.collect.ImmutableList;",
+            "import com.google.common.collect.Ordering;",
+            "import java.lang.annotation.RetentionPolicy;",
+            "import java.time.chrono.IsoEra;",
+            "",
+            "class A {",
+            "  {",
+            "    // The `List`-accepting overload is currently ignored.",
+            "    Ordering.explicit(ImmutableList.of(RetentionPolicy.SOURCE, RetentionPolicy.CLASS));",
+            "",
+            "    Ordering.explicit(IsoEra.BCE, IsoEra.CE);",
+            "    // BUG: Diagnostic contains: IsoEra.CE",
+            "    Ordering.explicit(IsoEra.BCE);",
+            "    // BUG: Diagnostic contains: IsoEra.BCE",
+            "    Ordering.explicit(IsoEra.CE);",
+            "",
+            "    Ordering.explicit(RetentionPolicy.SOURCE, RetentionPolicy.CLASS, RetentionPolicy.RUNTIME);",
+            "    // BUG: Diagnostic contains: RetentionPolicy.CLASS, RetentionPolicy.RUNTIME",
+            "    Ordering.explicit(RetentionPolicy.SOURCE);",
+            "    // BUG: Diagnostic contains: RetentionPolicy.SOURCE, RetentionPolicy.RUNTIME",
+            "    Ordering.explicit(RetentionPolicy.CLASS);",
+            "    // BUG: Diagnostic contains: RetentionPolicy.SOURCE, RetentionPolicy.CLASS",
+            "    Ordering.explicit(RetentionPolicy.RUNTIME);",
+            "    // BUG: Diagnostic contains: RetentionPolicy.RUNTIME",
+            "    Ordering.explicit(RetentionPolicy.SOURCE, RetentionPolicy.CLASS);",
+            "    // BUG: Diagnostic contains: RetentionPolicy.CLASS",
+            "    Ordering.explicit(RetentionPolicy.SOURCE, RetentionPolicy.RUNTIME);",
+            "    // BUG: Diagnostic contains: RetentionPolicy.SOURCE",
+            "    Ordering.explicit(RetentionPolicy.CLASS, RetentionPolicy.RUNTIME);",
+            "",
+            "    Ordering.explicit(BCE, CE);",
+            "    // BUG: Diagnostic contains: IsoEra.CE",
+            "    Ordering.explicit(BCE);",
+            "    // BUG: Diagnostic contains: IsoEra.BCE",
+            "    Ordering.explicit(CE);",
+            "",
+            "    Ordering.explicit(SOURCE, CLASS, RUNTIME);",
+            "    // BUG: Diagnostic contains: RetentionPolicy.CLASS, RetentionPolicy.RUNTIME",
+            "    Ordering.explicit(SOURCE);",
+            "    // BUG: Diagnostic contains: RetentionPolicy.SOURCE, RetentionPolicy.RUNTIME",
+            "    Ordering.explicit(CLASS);",
+            "    // BUG: Diagnostic contains: RetentionPolicy.SOURCE, RetentionPolicy.CLASS",
+            "    Ordering.explicit(RUNTIME);",
+            "    // BUG: Diagnostic contains: RetentionPolicy.RUNTIME",
+            "    Ordering.explicit(SOURCE, CLASS);",
+            "    // BUG: Diagnostic contains: RetentionPolicy.CLASS",
+            "    Ordering.explicit(SOURCE, RUNTIME);",
+            "    // BUG: Diagnostic contains: RetentionPolicy.SOURCE",
+            "    Ordering.explicit(CLASS, RUNTIME);",
+            "",
+            "    Ordering.explicit(RetentionPolicy.SOURCE, BCE, RetentionPolicy.CLASS, CE, RUNTIME);",
+            "    Ordering.explicit(SOURCE, IsoEra.BCE, CLASS, IsoEra.CE, RetentionPolicy.RUNTIME);",
+            "    // BUG: Diagnostic contains: RetentionPolicy.CLASS",
+            "    Ordering.explicit(RetentionPolicy.SOURCE, BCE, CE, RUNTIME);",
+            "    // BUG: Diagnostic contains: RetentionPolicy.CLASS",
+            "    Ordering.explicit(IsoEra.BCE, SOURCE, IsoEra.CE, RetentionPolicy.RUNTIME);",
+            "    // BUG: Diagnostic contains: IsoEra.CE, RetentionPolicy.RUNTIME",
+            "    Ordering.explicit(IsoEra.BCE, SOURCE, RetentionPolicy.CLASS);",
+            "    // BUG: Diagnostic contains: RetentionPolicy.SOURCE, IsoEra.BCE",
+            "    Ordering.explicit(CLASS, RUNTIME, CE);",
+            "  }",
+            "}")
+        .doTest();
+  }
+}

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

@@ -0,0 +1,122 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugCheckerRefactoringTestHelper.newInstance;
+
+import com.google.errorprone.BugCheckerRefactoringTestHelper;
+import com.google.errorprone.BugCheckerRefactoringTestHelper.FixChoosers;
+import com.google.errorprone.CompilationTestHelper;
+import org.junit.jupiter.api.Test;
+
+final class FluxFlatMapUsageTest {
+  private final CompilationTestHelper compilationTestHelper =
+      CompilationTestHelper.newInstance(FluxFlatMapUsage.class, getClass());
+  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
+      newInstance(FluxFlatMapUsage.class, getClass());
+
+  @Test
+  void identification() {
+    compilationTestHelper
+        .addSourceLines(
+            "A.java",
+            "import java.util.function.BiFunction;",
+            "import java.util.function.Function;",
+            "import reactor.core.publisher.Flux;",
+            "import reactor.core.publisher.Mono;",
+            "",
+            "class A {",
+            "  void m() {",
+            "    // BUG: Diagnostic contains:",
+            "    Flux.just(1).flatMap(Flux::just);",
+            "    // BUG: Diagnostic contains:",
+            "    Flux.just(1).<String>flatMap(i -> Flux.just(String.valueOf(i)));",
+            "    // BUG: Diagnostic contains:",
+            "    Flux.just(1).flatMapSequential(Flux::just);",
+            "    // BUG: Diagnostic contains:",
+            "    Flux.just(1).<String>flatMapSequential(i -> Flux.just(String.valueOf(i)));",
+            "",
+            "    Mono.just(1).flatMap(Mono::just);",
+            "    Flux.just(1).concatMap(Flux::just);",
+            "",
+            "    Flux.just(1).flatMap(Flux::just, 1);",
+            "    Flux.just(1).flatMap(Flux::just, 1, 1);",
+            "    Flux.just(1).flatMap(Flux::just, throwable -> Flux.empty(), Flux::empty);",
+            "",
+            "    Flux.just(1).flatMapSequential(Flux::just, 1);",
+            "    Flux.just(1).flatMapSequential(Flux::just, 1, 1);",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    this.<String, Flux<String>>sink(Flux::flatMap);",
+            "    // BUG: Diagnostic contains:",
+            "    this.<Integer, Flux<Integer>>sink(Flux::<Integer>flatMap);",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    this.<String, Flux<String>>sink(Flux::flatMapSequential);",
+            "    // BUG: Diagnostic contains:",
+            "    this.<Integer, Flux<Integer>>sink(Flux::<Integer>flatMapSequential);",
+            "",
+            "    this.<String, Mono<String>>sink(Mono::flatMap);",
+            "  }",
+            "",
+            "  private <T, P> void sink(BiFunction<P, Function<T, P>, P> fun) {}",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  void replacementFirstSuggestedFix() {
+    refactoringTestHelper
+        .setFixChooser(FixChoosers.FIRST)
+        .addInputLines(
+            "in/A.java",
+            "import reactor.core.publisher.Flux;",
+            "",
+            "class A {",
+            "  void m() {",
+            "    Flux.just(1).flatMap(Flux::just);",
+            "    Flux.just(1).flatMapSequential(Flux::just);",
+            "  }",
+            "}")
+        .addOutputLines(
+            "out/A.java",
+            "import reactor.core.publisher.Flux;",
+            "",
+            "class A {",
+            "  void m() {",
+            "    Flux.just(1).concatMap(Flux::just);",
+            "    Flux.just(1).concatMap(Flux::just);",
+            "  }",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  void replacementSecondSuggestedFix() {
+    refactoringTestHelper
+        .setFixChooser(FixChoosers.SECOND)
+        .addInputLines(
+            "in/A.java",
+            "import reactor.core.publisher.Flux;",
+            "",
+            "class A {",
+            "  private static final int MAX_CONCURRENCY = 8;",
+            "",
+            "  void m() {",
+            "    Flux.just(1).flatMap(Flux::just);",
+            "    Flux.just(1).flatMapSequential(Flux::just);",
+            "  }",
+            "}")
+        .addOutputLines(
+            "out/A.java",
+            "import reactor.core.publisher.Flux;",
+            "",
+            "class A {",
+            "  private static final int MAX_CONCURRENCY = 8;",
+            "",
+            "  void m() {",
+            "    Flux.just(1).flatMap(Flux::just, MAX_CONCURRENCY);",
+            "    Flux.just(1).flatMapSequential(Flux::just, MAX_CONCURRENCY);",
+            "  }",
+            "}")
+        .doTest();
+  }
+}

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

@@ -0,0 +1,413 @@
+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 FormatStringConcatenationTest {
+  private final CompilationTestHelper compilationTestHelper =
+      CompilationTestHelper.newInstance(FormatStringConcatenation.class, getClass());
+  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
+      BugCheckerRefactoringTestHelper.newInstance(FormatStringConcatenation.class, getClass());
+
+  @Test
+  void identification() {
+    compilationTestHelper
+        .addSourceLines(
+            "A.java",
+            "import static com.google.common.base.Preconditions.checkArgument;",
+            "import static com.google.common.base.Preconditions.checkNotNull;",
+            "import static com.google.common.base.Preconditions.checkState;",
+            "import static com.google.common.base.Verify.verify;",
+            "import static org.assertj.core.api.Assertions.assertThat;",
+            "import static org.assertj.core.api.SoftAssertions.assertSoftly;",
+            "",
+            "import java.util.Formatter;",
+            "import java.util.Locale;",
+            "import org.assertj.core.api.Assertions;",
+            "import org.assertj.core.api.BDDAssertions;",
+            "import org.assertj.core.api.Fail;",
+            "import org.assertj.core.api.ThrowableAssertAlternative;",
+            "import org.assertj.core.api.WithAssertions;",
+            "import org.slf4j.Logger;",
+            "import org.slf4j.LoggerFactory;",
+            "import org.slf4j.Marker;",
+            "",
+            "class A {",
+            "  private static final Logger LOG = LoggerFactory.getLogger(A.class);",
+            "",
+            "  void negative() {",
+            "    hashCode();",
+            "    equals(new A());",
+            "    equals(toString());",
+            "    equals(0);",
+            "    equals(\"str\");",
+            "    equals(\"str\" + 0);",
+            "    equals(0 + 0);",
+            "    equals(0 - 0);",
+            "    equals(\"str \" + toString());",
+            "  }",
+            "",
+            "  void assertj() {",
+            "    assertThat(0).overridingErrorMessage(toString());",
+            "    assertThat(0).overridingErrorMessage(\"str\");",
+            "    assertThat(0).overridingErrorMessage(\"str \" + 0);",
+            "    assertThat(0).overridingErrorMessage(\"str %s\", 2 * 3);",
+            "    assertThat(0).overridingErrorMessage(\"str %s\", toString());",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(0).overridingErrorMessage(\"str \" + hashCode() / 2);",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(0).overridingErrorMessage((\"str \" + toString()));",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(0).overridingErrorMessage(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(0).overridingErrorMessage(\"%s \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(0).withFailMessage(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(0).withFailMessage(\"%s \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    assertSoftly(softly -> softly.fail(\"str \" + toString()));",
+            "    // BUG: Diagnostic contains:",
+            "    assertSoftly(softly -> softly.fail(\"%s \" + toString(), \"arg\"));",
+            "    assertSoftly(softly -> softly.fail(\"str \" + toString(), new Throwable()));",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(\"\").isEqualTo(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(\"\").isEqualTo(\"%s \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(new Error()).hasMessage(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(new Error()).hasMessage(\"%s \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(new Error()).hasMessageContaining(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(new Error()).hasMessageContaining(\"%s \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(new Error()).hasMessageEndingWith(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(new Error()).hasMessageEndingWith(\"%s \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(new Error()).hasMessageStartingWith(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(new Error()).hasMessageStartingWith(\"%s \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(new Error()).hasRootCauseMessage(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(new Error()).hasRootCauseMessage(\"%s \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(new Error()).hasStackTraceContaining(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(new Error()).hasStackTraceContaining(\"%s \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(0).as(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(0).as(\"%s \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(0).describedAs(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    assertThat(0).describedAs(\"%s \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    ((ThrowableAssertAlternative) null).withMessage(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    ((ThrowableAssertAlternative) null).withMessage(\"%s \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    ((ThrowableAssertAlternative) null).withMessageContaining(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    ((ThrowableAssertAlternative) null).withMessageContaining(\"%s \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    ((ThrowableAssertAlternative) null).withMessageEndingWith(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    ((ThrowableAssertAlternative) null).withMessageEndingWith(\"%s \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    ((ThrowableAssertAlternative) null).withMessageStartingWith(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    ((ThrowableAssertAlternative) null).withMessageStartingWith(\"%s \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    ((ThrowableAssertAlternative) null).withStackTraceContaining(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    ((ThrowableAssertAlternative) null).withStackTraceContaining(\"%s \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    ((WithAssertions) null).fail(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    ((WithAssertions) null).fail(\"%s \" + toString(), \"arg\");",
+            "    ((WithAssertions) null).fail(\"str \" + toString(), new Throwable());",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    Assertions.fail(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    Assertions.fail(\"%s \" + toString(), \"arg\");",
+            "    Assertions.fail(\"str \" + toString(), new Throwable());",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    BDDAssertions.fail(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    BDDAssertions.fail(\"%s \" + toString(), \"arg\");",
+            "    BDDAssertions.fail(\"str \" + toString(), new Throwable());",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    Fail.fail(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    Fail.fail(\"%s \" + toString(), \"arg\");",
+            "    Fail.fail(\"str \" + toString(), new Throwable());",
+            "  }",
+            "",
+            "  void guava() {",
+            "    checkArgument(true);",
+            "    checkArgument(true, toString());",
+            "    checkArgument(true, \"str\");",
+            "    checkArgument(true, \"str \" + 0);",
+            "    checkArgument(true, \"str %s\", 2 * 3);",
+            "    checkArgument(true, \"str %s\", toString());",
+            "    // BUG: Diagnostic contains:",
+            "    checkArgument(true, \"str \" + hashCode() / 2);",
+            "    // BUG: Diagnostic contains:",
+            "    checkArgument(true, (\"str \" + toString()));",
+            "    // BUG: Diagnostic contains:",
+            "    checkArgument(true, \"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    checkArgument(true, \"%s \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    checkNotNull(true, \"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    checkNotNull(true, \"%s \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    checkState(true, \"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    checkState(true, \"%s \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    verify(true, \"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    verify(true, \"%s \" + toString(), \"arg\");",
+            "  }",
+            "",
+            "  void jdk() {",
+            "    String.format(\"str\");",
+            "    String.format(\"str \" + 0);",
+            "    String.format(\"str {}\", 2 * 3);",
+            "    String.format(\"str {}\", toString());",
+            "    // BUG: Diagnostic contains:",
+            "    String.format(\"str \" + hashCode() / 2);",
+            "    // BUG: Diagnostic contains:",
+            "    String.format((\"str \" + toString()));",
+            "    // BUG: Diagnostic contains:",
+            "    String.format(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    String.format(\"{} \" + toString(), \"arg\");",
+            "",
+            "    String.format(Locale.ROOT, \"str\");",
+            "    String.format(Locale.ROOT, \"str \" + 0);",
+            "    String.format(Locale.ROOT, \"str {}\", 2 * 3);",
+            "    String.format(Locale.ROOT, \"str {}\", toString());",
+            "    // BUG: Diagnostic contains:",
+            "    String.format(Locale.ROOT, (\"str \" + toString()));",
+            "    // BUG: Diagnostic contains:",
+            "    String.format(Locale.ROOT, \"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    String.format(Locale.ROOT, \"{} \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    new Formatter().format(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    new Formatter().format(\"{} \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    new Formatter().format(Locale.ROOT, \"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    new Formatter().format(Locale.ROOT, \"{} \" + toString(), \"arg\");",
+            "  }",
+            "",
+            "  void slf4j() {",
+            "    LOG.debug(\"str\");",
+            "    LOG.debug(\"str \" + 0);",
+            "    LOG.debug(\"str {}\", 2 * 3);",
+            "    LOG.debug(\"str {}\", toString());",
+            "    // BUG: Diagnostic contains:",
+            "    LOG.debug(\"str \" + hashCode() / 2);",
+            "    // BUG: Diagnostic contains:",
+            "    LOG.debug((\"str \" + toString()));",
+            "    // BUG: Diagnostic contains:",
+            "    LOG.debug(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    LOG.debug(\"{} \" + toString(), \"arg\");",
+            "",
+            "    LOG.debug((Marker) null, \"str\");",
+            "    LOG.debug((Marker) null, \"str \" + 0);",
+            "    LOG.debug((Marker) null, \"str {}\", 2 * 3);",
+            "    LOG.debug((Marker) null, \"str {}\", toString());",
+            "    // BUG: Diagnostic contains:",
+            "    LOG.debug((Marker) null, (\"str \" + toString()));",
+            "    // BUG: Diagnostic contains:",
+            "    LOG.debug((Marker) null, \"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    LOG.debug((Marker) null, \"{} \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    LOG.error(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    LOG.error(\"{} \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    LOG.error((Marker) null, \"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    LOG.error((Marker) null, \"{} \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    LOG.info(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    LOG.info(\"{} \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    LOG.info((Marker) null, \"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    LOG.info((Marker) null, \"{} \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    LOG.trace(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    LOG.trace(\"{} \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    LOG.trace((Marker) null, \"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    LOG.trace((Marker) null, \"{} \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    LOG.warn(\"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    LOG.warn(\"{} \" + toString(), \"arg\");",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    LOG.warn((Marker) null, \"str \" + toString());",
+            "    // BUG: Diagnostic contains:",
+            "    LOG.warn((Marker) null, \"{} \" + toString(), \"arg\");",
+            "  }",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  void replacement() {
+    refactoringTestHelper
+        .addInputLines(
+            "in/A.java",
+            "import static com.google.common.base.Preconditions.checkArgument;",
+            "import static org.assertj.core.api.Assertions.assertThat;",
+            "",
+            "import java.util.Locale;",
+            "import org.slf4j.Logger;",
+            "import org.slf4j.LoggerFactory;",
+            "import org.slf4j.Marker;",
+            "",
+            "class A {",
+            "  private static final Logger LOG = LoggerFactory.getLogger(A.class);",
+            "",
+            "  void assertj() {",
+            "    assertThat(0).overridingErrorMessage(toString() + \" str\");",
+            "    assertThat(0).overridingErrorMessage(\"str \" + toString());",
+            "    assertThat(0).overridingErrorMessage(toString() + toString());",
+            "    assertThat(0).overridingErrorMessage(\"str \" + toString() + \" word \" + new A().hashCode());",
+            "    assertThat(0).overridingErrorMessage(\"str \" + (toString() + \" word \") + (hashCode() / 2));",
+            "",
+            "    // Flagged but not auto-fixed.",
+            "    assertThat(0).overridingErrorMessage(\"%s \" + toString(), \"arg\");",
+            "  }",
+            "",
+            "  void guava() {",
+            "    checkArgument(true, \"str \" + toString());",
+            "",
+            "    // Flagged but not auto-fixed.",
+            "    checkArgument(true, \"%s \" + toString(), \"arg\");",
+            "  }",
+            "",
+            "  void jdk() {",
+            "    String.format(\"str \" + toString());",
+            "    String.format(Locale.ROOT, \"str \" + toString());",
+            "",
+            "    // Flagged but not auto-fixed.",
+            "    String.format(\"{} \" + toString(), \"arg\");",
+            "    String.format(Locale.ROOT, \"{} \" + toString(), \"arg\");",
+            "  }",
+            "",
+            "  void slf4j() {",
+            "    LOG.debug(\"str \" + toString());",
+            "    LOG.debug((Marker) null, \"str \" + toString());",
+            "",
+            "    // Flagged but not auto-fixed.",
+            "    LOG.debug(\"{} \" + toString(), \"arg\");",
+            "    LOG.debug((Marker) null, \"{} \" + toString(), \"arg\");",
+            "  }",
+            "}")
+        .addOutputLines(
+            "out/A.java",
+            "import static com.google.common.base.Preconditions.checkArgument;",
+            "import static org.assertj.core.api.Assertions.assertThat;",
+            "",
+            "import java.util.Locale;",
+            "import org.slf4j.Logger;",
+            "import org.slf4j.LoggerFactory;",
+            "import org.slf4j.Marker;",
+            "",
+            "class A {",
+            "  private static final Logger LOG = LoggerFactory.getLogger(A.class);",
+            "",
+            "  void assertj() {",
+            "    assertThat(0).overridingErrorMessage(\"%s str\", toString());",
+            "    assertThat(0).overridingErrorMessage(\"str %s\", toString());",
+            "    assertThat(0).overridingErrorMessage(\"%s%s\", toString(), toString());",
+            "    assertThat(0).overridingErrorMessage(\"str %s word %s\", toString(), new A().hashCode());",
+            "    assertThat(0).overridingErrorMessage(\"str %s word %s\", toString(), hashCode() / 2);",
+            "",
+            "    // Flagged but not auto-fixed.",
+            "    assertThat(0).overridingErrorMessage(\"%s \" + toString(), \"arg\");",
+            "  }",
+            "",
+            "  void guava() {",
+            "    checkArgument(true, \"str %s\", toString());",
+            "",
+            "    // Flagged but not auto-fixed.",
+            "    checkArgument(true, \"%s \" + toString(), \"arg\");",
+            "  }",
+            "",
+            "  void jdk() {",
+            "    String.format(\"str %s\", toString());",
+            "    String.format(Locale.ROOT, \"str %s\", toString());",
+            "",
+            "    // Flagged but not auto-fixed.",
+            "    String.format(\"{} \" + toString(), \"arg\");",
+            "    String.format(Locale.ROOT, \"{} \" + toString(), \"arg\");",
+            "  }",
+            "",
+            "  void slf4j() {",
+            "    LOG.debug(\"str {}\", toString());",
+            "    LOG.debug((Marker) null, \"str {}\", toString());",
+            "",
+            "    // Flagged but not auto-fixed.",
+            "    LOG.debug(\"{} \" + toString(), \"arg\");",
+            "    LOG.debug((Marker) null, \"{} \" + toString(), \"arg\");",
+            "  }",
+            "}")
+        .doTest(TestMode.TEXT_MATCH);
+  }
+}