WIP (Use new SuggestedFix.mergeFixes())

See:
- https://github.com/spring-projects/spring-framework/wiki/Spring-Framework-6.2-Release-Notes
- https://github.com/spring-projects/spring-framework/releases/tag/v6.1.15
- https://github.com/spring-projects/spring-framework/releases/tag/v6.2.0-M1
- https://github.com/spring-projects/spring-framework/releases/tag/v6.2.0-M2
- https://github.com/spring-projects/spring-framework/releases/tag/v6.2.0-M3
- https://github.com/spring-projects/spring-framework/releases/tag/v6.2.0-M4
- https://github.com/spring-projects/spring-framework/releases/tag/v6.2.0-M5
- https://github.com/spring-projects/spring-framework/releases/tag/v6.2.0-M6
- https://github.com/spring-projects/spring-framework/releases/tag/v6.2.0-M7
- https://github.com/spring-projects/spring-framework/releases/tag/v6.2.0-RC1
- https://github.com/spring-projects/spring-framework/releases/tag/v6.2.0-RC2
- https://github.com/spring-projects/spring-framework/releases/tag/v6.2.0-RC3
- https://github.com/spring-projects/spring-framework/releases/tag/v6.2.0
- https://github.com/spring-projects/spring-framework/compare/v6.1.14...v6.2.0

.github/ISSUE_TEMPLATE/bug_report.md

@@ -42,9 +42,9 @@ Please replace this sentence with log output, if applicable.
 <!-- Please complete the following information: -->
 
 - Operating system (e.g. MacOS Monterey).
-- Java version (i.e. `java --version`, e.g. `17.0.10`).
-- Error Prone version (e.g. `2.25.0`).
-- Error Prone Support version (e.g. `0.15.0`).
+- Java version (i.e. `java --version`, e.g. `17.0.13`).
+- Error Prone version (e.g. `2.35.1`).
+- Error Prone Support version (e.g. `0.19.0`).
 
 ### Additional context
 

.github/workflows/build.yml

@@ -9,24 +9,24 @@ jobs:
   build:
     strategy:
       matrix:
-        os: [ ubuntu-22.04 ]
-        jdk: [ 17.0.10, 21.0.2 ]
+        os: [ ubuntu-24.04 ]
+        jdk: [ 17.0.13, 21.0.5, 23.0.1 ]
         distribution: [ temurin ]
         experimental: [ false ]
         include:
           - os: macos-14
-            jdk: 17.0.10
+            jdk: 17.0.13
             distribution: temurin
             experimental: false
           - os: windows-2022
-            jdk: 17.0.10
+            jdk: 17.0.13
             distribution: temurin
             experimental: false
     runs-on: ${{ matrix.os }}
     continue-on-error: ${{ matrix.experimental }}
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
+        uses: step-security/harden-runner@91182cccc01eb5e619899d80e4e971d6181294a7 # v2.10.1
         with:
           disable-sudo: true
           egress-policy: block
@@ -42,11 +42,11 @@ jobs:
       # additionally enabling all checks defined in this project and any Error
       # Prone checks available only from other artifact repositories.
       - name: Check out code and set up JDK and Maven
-        uses: s4u/setup-maven-action@489441643219d2b93ee2a127b2402eb640a1b947 # v1.13.0
+        uses: s4u/setup-maven-action@382542f77617f34e56bf83868920a4d45b7451e7 # v1.16.0
         with:
           java-version: ${{ matrix.jdk }}
           java-distribution: ${{ matrix.distribution }}
-          maven-version: 3.9.6
+          maven-version: 3.9.9
       - name: Display build environment details
         run: mvn --version
       - name: Build project against vanilla Error Prone, compile Javadoc
@@ -54,6 +54,6 @@ jobs:
       - name: Build project with self-check against Error Prone fork
         run: mvn -T1C clean verify -Perror-prone-fork -Pnon-maven-central -Pself-check -s settings.xml
       - name: Remove installed project artifacts
-        run: mvn build-helper:remove-project-artifact
+        run: mvn dependency:purge-local-repository -DmanualInclude='${project.groupId}' -DresolutionFuzziness=groupId
 
 # XXX: Enable Codecov once we "go public".

.github/workflows/codeql.yml

@@ -19,10 +19,10 @@ jobs:
     permissions:
       contents: read
       security-events: write
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
+        uses: step-security/harden-runner@91182cccc01eb5e619899d80e4e971d6181294a7 # v2.10.1
         with:
           disable-sudo: true
           egress-policy: block
@@ -34,11 +34,11 @@ jobs:
             repo.maven.apache.org:443
             uploads.github.com:443
       - name: Check out code and set up JDK and Maven
-        uses: s4u/setup-maven-action@489441643219d2b93ee2a127b2402eb640a1b947 # v1.13.0
+        uses: s4u/setup-maven-action@382542f77617f34e56bf83868920a4d45b7451e7 # v1.16.0
         with:
-          java-version: 17.0.10
+          java-version: 17.0.13
           java-distribution: temurin
-          maven-version: 3.9.6
+          maven-version: 3.9.9
       - name: Initialize CodeQL
         uses: github/codeql-action/init@c7f9125735019aa87cfc361530512d50ea439c71 # v3.25.1
         with:

.github/workflows/deploy-website.yml

@@ -9,10 +9,10 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
 jobs:
   build:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
+        uses: step-security/harden-runner@91182cccc01eb5e619899d80e4e971d6181294a7 # v2.10.1
         with:
           disable-sudo: true
           egress-policy: block
@@ -39,10 +39,10 @@ jobs:
             www.youtube.com:443
             youtrack.jetbrains.com:443
       - name: Check out code
-        uses: actions/checkout@a5ac7e51b41094c92402da3b24376905380afc29 # v4.1.6
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           persist-credentials: false
-      - uses: ruby/setup-ruby@6bd3d993c602f6b675728ebaecb2b569ff86e99b # v1.174.0
+      - uses: ruby/setup-ruby@7d3497fd78c07c0d84ebafa58d8dac60cd1f0763 # v1.199.0
         with:
           working-directory: ./website
           bundler-cache: true
@@ -68,13 +68,13 @@ jobs:
     permissions:
       id-token: write
       pages: write
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
     environment:
       name: github-pages
       url: ${{ steps.deployment.outputs.page_url }}
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
+        uses: step-security/harden-runner@91182cccc01eb5e619899d80e4e971d6181294a7 # v2.10.1
         with:
           disable-sudo: true
           egress-policy: block

.github/workflows/openssf-scorecard.yml

@@ -18,30 +18,31 @@ jobs:
       contents: read
       security-events: write
       id-token: write
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
+        uses: step-security/harden-runner@91182cccc01eb5e619899d80e4e971d6181294a7 # v2.10.1
         with:
           disable-sudo: true
           egress-policy: block
           allowed-endpoints: >
+            api.deps.dev:443
             api.github.com:443
             api.osv.dev:443
             api.scorecard.dev:443
             api.securityscorecards.dev:443
-            fulcio.sigstore.dev:443
             github.com:443
+            index.docker.io:443
             oss-fuzz-build-logs.storage.googleapis.com:443
-            rekor.sigstore.dev:443
-            tuf-repo-cdn.sigstore.dev:443
+            repo.maven.apache.org:443
+            *.sigstore.dev:443
             www.bestpractices.dev:443
       - name: Check out code
-        uses: actions/checkout@a5ac7e51b41094c92402da3b24376905380afc29 # v4.1.6
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           persist-credentials: false
       - name: Run OpenSSF Scorecard analysis
-        uses: ossf/scorecard-action@dc50aa9510b46c811795eb24b2f1ba02a914e534 # v2.3.3
+        uses: ossf/scorecard-action@62b2cac7ed8198b15735ed49ab1e5cf35480ba46 # v2.4.0
         with:
           results_file: results.sarif
           results_format: sarif

.github/workflows/pitest-analyze-pr.yml

@@ -9,10 +9,10 @@ permissions:
   contents: read
 jobs:
   analyze-pr:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
+        uses: step-security/harden-runner@91182cccc01eb5e619899d80e4e971d6181294a7 # v2.10.1
         with:
           disable-sudo: true
           egress-policy: block
@@ -22,12 +22,12 @@ jobs:
             objects.githubusercontent.com:443
             repo.maven.apache.org:443
       - name: Check out code and set up JDK and Maven
-        uses: s4u/setup-maven-action@489441643219d2b93ee2a127b2402eb640a1b947 # v1.13.0
+        uses: s4u/setup-maven-action@382542f77617f34e56bf83868920a4d45b7451e7 # v1.16.0
         with:
           checkout-fetch-depth: 2
-          java-version: 17.0.10
+          java-version: 17.0.13
           java-distribution: temurin
-          maven-version: 3.9.6
+          maven-version: 3.9.9
       - name: Run Pitest
         # By running with features `+GIT(from[HEAD~1]), +gitci`, Pitest only
         # analyzes lines changed in the associated pull request, as GitHub
@@ -38,7 +38,7 @@ jobs:
       - name: Aggregate Pitest reports
         run: mvn pitest-git:aggregate -DkilledEmoji=":tada:" -DmutantEmoji=":zombie:" -DtrailingText="Mutation testing report by [Pitest](https://pitest.org/). Review any surviving mutants by inspecting the line comments under [_Files changed_](${{ github.event.number }}/files)."
       - name: Upload Pitest reports as artifact
-        uses: actions/upload-artifact@65462800fd760344b1a7b4382951275a0abb4808 # v4.3.3
+        uses: actions/upload-artifact@b4b15b8c7c6ac21ea08fcf65892d2ee8f75cf882 # v4.4.3
         with:
           name: pitest-reports
           path: ./target/pit-reports-ci

.github/workflows/pitest-update-pr.yml

@@ -17,10 +17,10 @@ jobs:
       checks: write
       contents: read
       pull-requests: write
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
+        uses: step-security/harden-runner@91182cccc01eb5e619899d80e4e971d6181294a7 # v2.10.1
         with:
           disable-sudo: true
           egress-policy: block
@@ -31,11 +31,11 @@ jobs:
             objects.githubusercontent.com:443
             repo.maven.apache.org:443
       - name: Check out code and set up JDK and Maven
-        uses: s4u/setup-maven-action@489441643219d2b93ee2a127b2402eb640a1b947 # v1.13.0
+        uses: s4u/setup-maven-action@382542f77617f34e56bf83868920a4d45b7451e7 # v1.16.0
         with:
-          java-version: 17.0.10
+          java-version: 17.0.13
           java-distribution: temurin
-          maven-version: 3.9.6
+          maven-version: 3.9.9
       - name: Download Pitest analysis artifact
         uses: dawidd6/action-download-artifact@09f2f74827fd3a8607589e5ad7f9398816f540fe # v3.1.4
         with:

.github/workflows/run-integration-tests.yml

@@ -1,9 +1,9 @@
 # If requested by means of a pull request comment, runs integration tests
 # against the project, using the code found on the pull request branch.
-# XXX: Generalize this to a matrix build of multiple integration tests,
-# possibly using multiple JDK or OS versions.
-# XXX: Investigate whether the comment can specify which integration tests run
-# run. See this example of a dynamic build matrix:
+# XXX: Review whether then build matrix should also vary JDK or OS versions.
+# XXX: Support `/integration-test [name...]` comment syntax to specify the
+# subset of integration tests to run.
+# See this example of a dynamic build matrix:
 # https://docs.github.com/en/actions/learn-github-actions/expressions#example-returning-a-json-object
 name: "Integration tests"
 on:
@@ -16,16 +16,20 @@ jobs:
     name: On-demand integration test
     if: |
       github.event.issue.pull_request && contains(github.event.comment.body, '/integration-test')
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
+    strategy:
+      matrix:
+        integration-test: [ "checkstyle", "metrics" ]
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
+        uses: step-security/harden-runner@91182cccc01eb5e619899d80e4e971d6181294a7 # v2.10.1
         with:
           disable-sudo: true
           egress-policy: block
           allowed-endpoints: >
             api.adoptium.net:443
             checkstyle.org:443
+            example.com:80
             github.com:443
             objects.githubusercontent.com:443
             oss.sonatype.org:443
@@ -33,21 +37,21 @@ jobs:
             repo.maven.apache.org:443
             repository.sonatype.org:443
       - name: Check out code and set up JDK and Maven
-        uses: s4u/setup-maven-action@489441643219d2b93ee2a127b2402eb640a1b947 # v1.13.0
+        uses: s4u/setup-maven-action@382542f77617f34e56bf83868920a4d45b7451e7 # v1.16.0
         with:
           checkout-ref: "refs/pull/${{ github.event.issue.number }}/head"
-          java-version: 17.0.10
+          java-version: 17.0.13
           java-distribution: temurin
-          maven-version: 3.9.6
+          maven-version: 3.9.9
       - name: Install project to local Maven repository
         run: mvn -T1C install -DskipTests -Dverification.skip
       - name: Run integration test
-        run: xvfb-run ./integration-tests/checkstyle.sh "${{ runner.temp }}/artifacts"
+        run: xvfb-run "./integration-tests/${{ matrix.integration-test }}.sh" "${{ runner.temp }}/artifacts"
       - name: Upload artifacts on failure
         if: ${{ failure() }}
-        uses: actions/upload-artifact@65462800fd760344b1a7b4382951275a0abb4808 # v4.3.3
+        uses: actions/upload-artifact@b4b15b8c7c6ac21ea08fcf65892d2ee8f75cf882 # v4.4.3
         with:
-          name: integration-test-checkstyle
+          name: "integration-test-${{ matrix.integration-test }}"
           path: "${{ runner.temp }}/artifacts"
       - name: Remove installed project artifacts
-        run: mvn build-helper:remove-project-artifact
+        run: mvn dependency:purge-local-repository -DmanualInclude='${project.groupId}' -DresolutionFuzziness=groupId

.github/workflows/sonarcloud.yml

@@ -16,30 +16,31 @@ jobs:
     if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name == github.repository
     permissions:
       contents: read
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
+        uses: step-security/harden-runner@91182cccc01eb5e619899d80e4e971d6181294a7 # v2.10.1
         with:
           disable-sudo: true
           egress-policy: block
           allowed-endpoints: >
+            analysis-sensorcache-eu-central-1-prod.s3.amazonaws.com:443
             api.adoptium.net:443
-            api.sonarcloud.io:443
+            api.nuget.org:443
             ea6ne4j2sb.execute-api.eu-central-1.amazonaws.com:443
             github.com:443
             objects.githubusercontent.com:443
             repo.maven.apache.org:443
             sc-cleancode-sensorcache-eu-central-1-prod.s3.amazonaws.com:443
-            scanner.sonarcloud.io:443
+            *.sonarcloud.io:443
             sonarcloud.io:443
       - name: Check out code and set up JDK and Maven
-        uses: s4u/setup-maven-action@489441643219d2b93ee2a127b2402eb640a1b947 # v1.13.0
+        uses: s4u/setup-maven-action@382542f77617f34e56bf83868920a4d45b7451e7 # v1.16.0
         with:
           checkout-fetch-depth: 0
-          java-version: 17.0.10
+          java-version: 17.0.13
           java-distribution: temurin
-          maven-version: 3.9.6
+          maven-version: 3.9.9
       - name: Create missing `test` directory
         # XXX: Drop this step in favour of actually having a test.
         run: mkdir refaster-compiler/src/test

.renovaterc.json

@@ -3,11 +3,24 @@
   "extends": [
     "helpers:pinGitHubActionDigests"
   ],
+  "customManagers": [
+    {
+      "customType": "regex",
+      "fileMatch": [
+        "^integration-tests/.*(-init\\.patch|\\.sh)$"
+      ],
+      "matchStrings": [
+        "\\b(?<packageName>[a-z0-9_.-]+?:[a-z0-9_.-]+?):(?<currentValue>[^:]+?):[a-zA-Z0-9_-]+\\b",
+        "<version>(?<currentValue>.*?)<!-- Renovate: (?<packageName>.*?) --></version>"
+      ],
+      "datasourceTemplate": "maven"
+    }
+  ],
   "packageRules": [
     {
-      "matchPackagePatterns": [
-        "^org\\.springframework:spring-framework-bom$",
-        "^org\\.springframework\\.boot:spring-boot[a-z-]*$"
+      "matchPackageNames": [
+        "/^org\\.springframework:spring-framework-bom$/",
+        "/^org\\.springframework\\.boot:spring-boot[a-z-]*$/"
       ],
       "separateMinorPatch": true
     },

README.md

@@ -302,7 +302,7 @@ channel; please see our [security policy][security] for details.
 [refaster]: https://errorprone.info/docs/refaster
 [refaster-rules-bigdecimal]: https://github.com/PicnicSupermarket/error-prone-support/blob/master/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/BigDecimalRules.java
 [refaster-rules]: https://github.com/PicnicSupermarket/error-prone-support/blob/master/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/
-[reproducible-builds-badge]: https://img.shields.io/badge/Reproducible_Builds-ok-success?labelColor=1e5b96
+[reproducible-builds-badge]: https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/jvm-repo-rebuild/reproducible-central/master/content/tech/picnic/error-prone-support/error-prone-support/badge.json
 [reproducible-builds-report]: https://github.com/jvm-repo-rebuild/reproducible-central/blob/master/content/tech/picnic/error-prone-support/error-prone-support/README.md
 [script-apply-error-prone-suggestions]: https://github.com/PicnicSupermarket/error-prone-support/blob/master/apply-error-prone-suggestions.sh
 [script-run-branch-mutation-tests]: https://github.com/PicnicSupermarket/error-prone-support/blob/master/run-branch-mutation-tests.sh

documentation-support/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.17.0</version>
+        <version>0.19.2-SNAPSHOT</version>
     </parent>
 
     <artifactId>documentation-support</artifactId>
@@ -33,6 +33,15 @@
             <artifactId>error_prone_test_helpers</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>${project.groupId}</groupId>
+            <artifactId>error-prone-utils</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>${project.groupId}</groupId>
+            <artifactId>refaster-test-support</artifactId>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-annotations</artifactId>

documentation-support/src/main/java/tech/picnic/errorprone/documentation/BugPatternTestExtractor.java

@@ -27,7 +27,7 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
 import org.jspecify.annotations.Nullable;
-import tech.picnic.errorprone.documentation.BugPatternTestExtractor.TestCases;
+import tech.picnic.errorprone.documentation.BugPatternTestExtractor.BugPatternTestCases;
 
 /**
  * An {@link Extractor} that describes how to extract data from classes that test a {@code
@@ -40,7 +40,7 @@ import tech.picnic.errorprone.documentation.BugPatternTestExtractor.TestCases;
 @Immutable
 @AutoService(Extractor.class)
 @SuppressWarnings("rawtypes" /* See https://github.com/google/auto/issues/870. */)
-public final class BugPatternTestExtractor implements Extractor<TestCases> {
+public final class BugPatternTestExtractor implements Extractor<BugPatternTestCases> {
   /** Instantiates a new {@link BugPatternTestExtractor} instance. */
   public BugPatternTestExtractor() {}
 
@@ -50,7 +50,7 @@ public final class BugPatternTestExtractor implements Extractor<TestCases> {
   }
 
   @Override
-  public Optional<TestCases> tryExtract(ClassTree tree, VisitorState state) {
+  public Optional<BugPatternTestCases> tryExtract(ClassTree tree, VisitorState state) {
     BugPatternTestCollector collector = new BugPatternTestCollector();
 
     collector.scan(tree, state);
@@ -59,7 +59,7 @@ public final class BugPatternTestExtractor implements Extractor<TestCases> {
         .filter(not(ImmutableList::isEmpty))
         .map(
             tests ->
-                new AutoValue_BugPatternTestExtractor_TestCases(
+                new AutoValue_BugPatternTestExtractor_BugPatternTestCases(
                     state.getPath().getCompilationUnit().getSourceFile().toUri(),
                     ASTHelpers.getSymbol(tree).className(),
                     tests));
@@ -95,10 +95,10 @@ public final class BugPatternTestExtractor implements Extractor<TestCases> {
             .onDescendantOf("com.google.errorprone.BugCheckerRefactoringTestHelper.ExpectOutput")
             .namedAnyOf("addOutputLines", "expectUnchanged");
 
-    private final List<TestCase> collectedTestCases = new ArrayList<>();
+    private final List<BugPatternTestCase> collectedBugPatternTestCases = new ArrayList<>();
 
-    private ImmutableList<TestCase> getCollectedTests() {
-      return ImmutableList.copyOf(collectedTestCases);
+    private ImmutableList<BugPatternTestCase> getCollectedTests() {
+      return ImmutableList.copyOf(collectedBugPatternTestCases);
     }
 
     @Override
@@ -110,14 +110,14 @@ public final class BugPatternTestExtractor implements Extractor<TestCases> {
                 classUnderTest -> {
                   List<TestEntry> entries = new ArrayList<>();
                   if (isReplacementTest) {
-                    extractReplacementTestCases(node, entries, state);
+                    extractReplacementBugPatternTestCases(node, entries, state);
                   } else {
-                    extractIdentificationTestCases(node, entries, state);
+                    extractIdentificationBugPatternTestCases(node, entries, state);
                   }
 
                   if (!entries.isEmpty()) {
-                    collectedTestCases.add(
-                        new AutoValue_BugPatternTestExtractor_TestCase(
+                    collectedBugPatternTestCases.add(
+                        new AutoValue_BugPatternTestExtractor_BugPatternTestCase(
                             classUnderTest, ImmutableList.copyOf(entries).reverse()));
                   }
                 });
@@ -140,7 +140,7 @@ public final class BugPatternTestExtractor implements Extractor<TestCases> {
           : Optional.empty();
     }
 
-    private static void extractIdentificationTestCases(
+    private static void extractIdentificationBugPatternTestCases(
         MethodInvocationTree tree, List<TestEntry> sink, VisitorState state) {
       if (IDENTIFICATION_SOURCE_LINES.matches(tree, state)) {
         String path = ASTHelpers.constValue(tree.getArguments().get(0), String.class);
@@ -155,11 +155,11 @@ public final class BugPatternTestExtractor implements Extractor<TestCases> {
 
       ExpressionTree receiver = ASTHelpers.getReceiver(tree);
       if (receiver instanceof MethodInvocationTree methodInvocation) {
-        extractIdentificationTestCases(methodInvocation, sink, state);
+        extractIdentificationBugPatternTestCases(methodInvocation, sink, state);
       }
     }
 
-    private static void extractReplacementTestCases(
+    private static void extractReplacementBugPatternTestCases(
         MethodInvocationTree tree, List<TestEntry> sink, VisitorState state) {
       if (REPLACEMENT_OUTPUT_SOURCE_LINES.matches(tree, state)) {
         /*
@@ -185,7 +185,7 @@ public final class BugPatternTestExtractor implements Extractor<TestCases> {
 
       ExpressionTree receiver = ASTHelpers.getReceiver(tree);
       if (receiver instanceof MethodInvocationTree methodInvocation) {
-        extractReplacementTestCases(methodInvocation, sink, state);
+        extractReplacementBugPatternTestCases(methodInvocation, sink, state);
       }
     }
 
@@ -208,24 +208,26 @@ public final class BugPatternTestExtractor implements Extractor<TestCases> {
   }
 
   @AutoValue
-  @JsonDeserialize(as = AutoValue_BugPatternTestExtractor_TestCases.class)
-  abstract static class TestCases {
-    static TestCases create(URI source, String testClass, ImmutableList<TestCase> testCases) {
-      return new AutoValue_BugPatternTestExtractor_TestCases(source, testClass, testCases);
+  @JsonDeserialize(as = AutoValue_BugPatternTestExtractor_BugPatternTestCases.class)
+  abstract static class BugPatternTestCases {
+    static BugPatternTestCases create(
+        URI source, String testClass, ImmutableList<BugPatternTestCase> testCases) {
+      return new AutoValue_BugPatternTestExtractor_BugPatternTestCases(
+          source, testClass, testCases);
     }
 
     abstract URI source();
 
     abstract String testClass();
 
-    abstract ImmutableList<TestCase> testCases();
+    abstract ImmutableList<BugPatternTestCase> testCases();
   }
 
   @AutoValue
-  @JsonDeserialize(as = AutoValue_BugPatternTestExtractor_TestCase.class)
-  abstract static class TestCase {
-    static TestCase create(String classUnderTest, ImmutableList<TestEntry> entries) {
-      return new AutoValue_BugPatternTestExtractor_TestCase(classUnderTest, entries);
+  @JsonDeserialize(as = AutoValue_BugPatternTestExtractor_BugPatternTestCase.class)
+  abstract static class BugPatternTestCase {
+    static BugPatternTestCase create(String classUnderTest, ImmutableList<TestEntry> entries) {
+      return new AutoValue_BugPatternTestExtractor_BugPatternTestCase(classUnderTest, entries);
     }
 
     abstract String classUnderTest();

documentation-support/src/main/java/tech/picnic/errorprone/documentation/DocumentationGeneratorTaskListener.java

@@ -14,7 +14,6 @@ import java.io.IOException;
 import java.net.URI;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.nio.file.Paths;
 import java.util.ServiceLoader;
 import javax.tools.JavaFileObject;
 
@@ -87,6 +86,6 @@ final class DocumentationGeneratorTaskListener implements TaskListener {
   }
 
   private static String getSimpleClassName(URI path) {
-    return Paths.get(path).getFileName().toString().replace(".java", "");
+    return Path.of(path).getFileName().toString().replace(".java", "");
   }
 }

documentation-support/src/main/java/tech/picnic/errorprone/documentation/RefasterRuleCollectionTestExtractor.java

@@ -0,0 +1,176 @@
+package tech.picnic.errorprone.documentation;
+
+import static com.google.common.collect.ImmutableList.toImmutableList;
+import static com.google.errorprone.matchers.Matchers.isSubtypeOf;
+import static java.util.stream.Collectors.joining;
+
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+import com.google.auto.service.AutoService;
+import com.google.auto.value.AutoValue;
+import com.google.common.base.Splitter;
+import com.google.common.base.Supplier;
+import com.google.common.base.VerifyException;
+import com.google.common.collect.ImmutableList;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.annotations.FormatMethod;
+import com.google.errorprone.annotations.Immutable;
+import com.google.errorprone.matchers.Matcher;
+import com.sun.source.tree.ClassTree;
+import com.sun.source.tree.MethodTree;
+import java.net.URI;
+import java.util.Optional;
+import java.util.regex.Pattern;
+import tech.picnic.errorprone.documentation.RefasterRuleCollectionTestExtractor.RefasterTestCases;
+import tech.picnic.errorprone.utils.SourceCode;
+
+/**
+ * An {@link Extractor} that describes how to extract data from Refaster rule input and output test
+ * classes.
+ */
+// XXX: Drop this extractor if/when the Refaster test framework is reimplemented such that tests can
+// be located alongside rules, rather than in two additional resource files as currently required by
+// `RefasterRuleCollection`.
+@Immutable
+@AutoService(Extractor.class)
+@SuppressWarnings("rawtypes" /* See https://github.com/google/auto/issues/870. */)
+public final class RefasterRuleCollectionTestExtractor implements Extractor<RefasterTestCases> {
+  private static final Matcher<ClassTree> IS_REFASTER_RULE_COLLECTION_TEST_CASE =
+      isSubtypeOf("tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase");
+  private static final Pattern TEST_CLASS_NAME_PATTERN = Pattern.compile("(.*)Test");
+  private static final Pattern TEST_CLASS_FILE_NAME_PATTERN =
+      Pattern.compile(".*(Input|Output)\\.java");
+  private static final Pattern TEST_METHOD_NAME_PATTERN = Pattern.compile("test(.*)");
+  private static final String LINE_SEPARATOR = "\n";
+  private static final Splitter LINE_SPLITTER = Splitter.on(LINE_SEPARATOR);
+
+  /** Instantiates a new {@link RefasterRuleCollectionTestExtractor} instance. */
+  public RefasterRuleCollectionTestExtractor() {}
+
+  @Override
+  public String identifier() {
+    return "refaster-rule-collection-test";
+  }
+
+  @Override
+  public Optional<RefasterTestCases> tryExtract(ClassTree tree, VisitorState state) {
+    if (!IS_REFASTER_RULE_COLLECTION_TEST_CASE.matches(tree, state)) {
+      return Optional.empty();
+    }
+
+    URI sourceFile = state.getPath().getCompilationUnit().getSourceFile().toUri();
+    return Optional.of(
+        RefasterTestCases.create(
+            sourceFile,
+            getRuleCollectionName(tree),
+            isInputFile(sourceFile),
+            getRefasterTestCases(tree, state)));
+  }
+
+  private static String getRuleCollectionName(ClassTree tree) {
+    String className = tree.getSimpleName().toString();
+
+    // XXX: Instead of throwing an error here, it'd be nicer to have a bug checker validate key
+    // aspects of `RefasterRuleCollectionTestCase` subtypes.
+    return tryExtractPatternGroup(className, TEST_CLASS_NAME_PATTERN)
+        .orElseThrow(
+            violation(
+                "Refaster rule collection test class name '%s' does not match '%s'",
+                className, TEST_CLASS_NAME_PATTERN));
+  }
+
+  private static boolean isInputFile(URI sourceFile) {
+    String path = sourceFile.getPath();
+
+    // XXX: Instead of throwing an error here, it'd be nicer to have a bug checker validate key
+    // aspects of `RefasterRuleCollectionTestCase` subtypes.
+    return "Input"
+        .equals(
+            tryExtractPatternGroup(path, TEST_CLASS_FILE_NAME_PATTERN)
+                .orElseThrow(
+                    violation(
+                        "Refaster rule collection test file name '%s' does not match '%s'",
+                        path, TEST_CLASS_FILE_NAME_PATTERN)));
+  }
+
+  private static ImmutableList<RefasterTestCase> getRefasterTestCases(
+      ClassTree tree, VisitorState state) {
+    return tree.getMembers().stream()
+        .filter(MethodTree.class::isInstance)
+        .map(MethodTree.class::cast)
+        .flatMap(m -> tryExtractRefasterTestCase(m, state).stream())
+        .collect(toImmutableList());
+  }
+
+  private static Optional<RefasterTestCase> tryExtractRefasterTestCase(
+      MethodTree method, VisitorState state) {
+    return tryExtractPatternGroup(method.getName().toString(), TEST_METHOD_NAME_PATTERN)
+        .map(name -> RefasterTestCase.create(name, getFormattedSource(method, state)));
+  }
+
+  /**
+   * Returns the source code for the specified method.
+   *
+   * @implNote This operation attempts to trim leading whitespace, such that the start and end of
+   *     the method declaration are aligned. The implemented heuristic assumes that the code is
+   *     formatted using Google Java Format.
+   */
+  // XXX: Leading Javadoc and other comments are currently not extracted. Consider fixing this.
+  private static String getFormattedSource(MethodTree method, VisitorState state) {
+    String source = SourceCode.treeToString(method, state);
+    int finalNewline = source.lastIndexOf(LINE_SEPARATOR);
+    if (finalNewline < 0) {
+      return source;
+    }
+
+    int indentation = Math.max(0, source.lastIndexOf(' ') - finalNewline);
+    String prefixToStrip = " ".repeat(indentation);
+
+    return LINE_SPLITTER
+        .splitToStream(source)
+        .map(line -> line.startsWith(prefixToStrip) ? line.substring(indentation) : line)
+        .collect(joining(LINE_SEPARATOR));
+  }
+
+  private static Optional<String> tryExtractPatternGroup(String input, Pattern pattern) {
+    java.util.regex.Matcher matcher = pattern.matcher(input);
+    return matcher.matches() ? Optional.of(matcher.group(1)) : Optional.empty();
+  }
+
+  @FormatMethod
+  private static Supplier<VerifyException> violation(String format, Object... args) {
+    return () -> new VerifyException(String.format(format, args));
+  }
+
+  @AutoValue
+  @JsonDeserialize(as = AutoValue_RefasterRuleCollectionTestExtractor_RefasterTestCases.class)
+  abstract static class RefasterTestCases {
+    static RefasterTestCases create(
+        URI source,
+        String ruleCollection,
+        boolean isInput,
+        ImmutableList<RefasterTestCase> testCases) {
+      return new AutoValue_RefasterRuleCollectionTestExtractor_RefasterTestCases(
+          source, ruleCollection, isInput, testCases);
+    }
+
+    abstract URI source();
+
+    abstract String ruleCollection();
+
+    abstract boolean isInput();
+
+    abstract ImmutableList<RefasterTestCase> testCases();
+  }
+
+  @AutoValue
+  @JsonDeserialize(as = AutoValue_RefasterRuleCollectionTestExtractor_RefasterTestCase.class)
+  abstract static class RefasterTestCase {
+    static RefasterTestCase create(String name, String content) {
+      return new AutoValue_RefasterRuleCollectionTestExtractor_RefasterTestCase(name, content);
+    }
+
+    abstract String name();
+
+    abstract String content();
+  }
+}

documentation-support/src/test/java/tech/picnic/errorprone/documentation/BugPatternTestExtractorTest.java

@@ -7,10 +7,10 @@ import java.net.URI;
 import java.nio.file.Path;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
+import tech.picnic.errorprone.documentation.BugPatternTestExtractor.BugPatternTestCase;
+import tech.picnic.errorprone.documentation.BugPatternTestExtractor.BugPatternTestCases;
 import tech.picnic.errorprone.documentation.BugPatternTestExtractor.IdentificationTestEntry;
 import tech.picnic.errorprone.documentation.BugPatternTestExtractor.ReplacementTestEntry;
-import tech.picnic.errorprone.documentation.BugPatternTestExtractor.TestCase;
-import tech.picnic.errorprone.documentation.BugPatternTestExtractor.TestCases;
 
 final class BugPatternTestExtractorTest {
   @Test
@@ -269,11 +269,11 @@ final class BugPatternTestExtractorTest {
     verifyGeneratedFileContent(
         outputDirectory,
         "SingleFileCompilationTestHelperTest",
-        TestCases.create(
+        BugPatternTestCases.create(
             URI.create("file:///SingleFileCompilationTestHelperTest.java"),
             "SingleFileCompilationTestHelperTest",
             ImmutableList.of(
-                TestCase.create(
+                BugPatternTestCase.create(
                     "SingleFileCompilationTestHelperTest.TestChecker",
                     ImmutableList.of(
                         IdentificationTestEntry.create(
@@ -302,11 +302,11 @@ final class BugPatternTestExtractorTest {
     verifyGeneratedFileContent(
         outputDirectory,
         "SingleFileCompilationTestHelperWithSetArgsTest",
-        TestCases.create(
+        BugPatternTestCases.create(
             URI.create("file:///SingleFileCompilationTestHelperWithSetArgsTest.java"),
             "SingleFileCompilationTestHelperWithSetArgsTest",
             ImmutableList.of(
-                TestCase.create(
+                BugPatternTestCase.create(
                     "SingleFileCompilationTestHelperWithSetArgsTest.TestChecker",
                     ImmutableList.of(
                         IdentificationTestEntry.create(
@@ -335,11 +335,11 @@ final class BugPatternTestExtractorTest {
     verifyGeneratedFileContent(
         outputDirectory,
         "MultiFileCompilationTestHelperTest",
-        TestCases.create(
+        BugPatternTestCases.create(
             URI.create("file:///MultiFileCompilationTestHelperTest.java"),
             "MultiFileCompilationTestHelperTest",
             ImmutableList.of(
-                TestCase.create(
+                BugPatternTestCase.create(
                     "MultiFileCompilationTestHelperTest.TestChecker",
                     ImmutableList.of(
                         IdentificationTestEntry.create(
@@ -370,11 +370,11 @@ final class BugPatternTestExtractorTest {
     verifyGeneratedFileContent(
         outputDirectory,
         "SingleFileBugCheckerRefactoringTestHelperTest",
-        TestCases.create(
+        BugPatternTestCases.create(
             URI.create("file:///SingleFileBugCheckerRefactoringTestHelperTest.java"),
             "SingleFileBugCheckerRefactoringTestHelperTest",
             ImmutableList.of(
-                TestCase.create(
+                BugPatternTestCase.create(
                     "SingleFileBugCheckerRefactoringTestHelperTest.TestChecker",
                     ImmutableList.of(
                         ReplacementTestEntry.create(
@@ -408,12 +408,12 @@ final class BugPatternTestExtractorTest {
     verifyGeneratedFileContent(
         outputDirectory,
         "SingleFileBugCheckerRefactoringTestHelperWithSetArgsFixChooserAndCustomTestModeTest",
-        TestCases.create(
+        BugPatternTestCases.create(
             URI.create(
                 "file:///SingleFileBugCheckerRefactoringTestHelperWithSetArgsFixChooserAndCustomTestModeTest.java"),
             "SingleFileBugCheckerRefactoringTestHelperWithSetArgsFixChooserAndCustomTestModeTest",
             ImmutableList.of(
-                TestCase.create(
+                BugPatternTestCase.create(
                     "SingleFileBugCheckerRefactoringTestHelperWithSetArgsFixChooserAndCustomTestModeTest.TestChecker",
                     ImmutableList.of(
                         ReplacementTestEntry.create(
@@ -444,11 +444,11 @@ final class BugPatternTestExtractorTest {
     verifyGeneratedFileContent(
         outputDirectory,
         "MultiFileBugCheckerRefactoringTestHelperTest",
-        TestCases.create(
+        BugPatternTestCases.create(
             URI.create("file:///MultiFileBugCheckerRefactoringTestHelperTest.java"),
             "MultiFileBugCheckerRefactoringTestHelperTest",
             ImmutableList.of(
-                TestCase.create(
+                BugPatternTestCase.create(
                     "MultiFileBugCheckerRefactoringTestHelperTest.TestChecker",
                     ImmutableList.of(
                         ReplacementTestEntry.create(
@@ -484,16 +484,16 @@ final class BugPatternTestExtractorTest {
     verifyGeneratedFileContent(
         outputDirectory,
         "CompilationAndBugCheckerRefactoringTestHelpersTest",
-        TestCases.create(
+        BugPatternTestCases.create(
             URI.create("file:///CompilationAndBugCheckerRefactoringTestHelpersTest.java"),
             "CompilationAndBugCheckerRefactoringTestHelpersTest",
             ImmutableList.of(
-                TestCase.create(
+                BugPatternTestCase.create(
                     "CompilationAndBugCheckerRefactoringTestHelpersTest.TestChecker",
                     ImmutableList.of(
                         IdentificationTestEntry.create(
                             "A.java", "// BUG: Diagnostic contains:\nclass A {}\n"))),
-                TestCase.create(
+                BugPatternTestCase.create(
                     "CompilationAndBugCheckerRefactoringTestHelpersTest.TestChecker",
                     ImmutableList.of(
                         ReplacementTestEntry.create(
@@ -532,17 +532,17 @@ final class BugPatternTestExtractorTest {
     verifyGeneratedFileContent(
         outputDirectory,
         "CompilationAndBugCheckerRefactoringTestHelpersWithCustomCheckerPackageAndNamesTest",
-        TestCases.create(
+        BugPatternTestCases.create(
             URI.create(
                 "file:///CompilationAndBugCheckerRefactoringTestHelpersWithCustomCheckerPackageAndNamesTest.java"),
             "pkg.CompilationAndBugCheckerRefactoringTestHelpersWithCustomCheckerPackageAndNamesTest",
             ImmutableList.of(
-                TestCase.create(
+                BugPatternTestCase.create(
                     "pkg.CompilationAndBugCheckerRefactoringTestHelpersWithCustomCheckerPackageAndNamesTest.CustomTestChecker",
                     ImmutableList.of(
                         IdentificationTestEntry.create(
                             "A.java", "// BUG: Diagnostic contains:\nclass A {}\n"))),
-                TestCase.create(
+                BugPatternTestCase.create(
                     "pkg.CompilationAndBugCheckerRefactoringTestHelpersWithCustomCheckerPackageAndNamesTest.CustomTestChecker2",
                     ImmutableList.of(
                         ReplacementTestEntry.create(
@@ -550,9 +550,9 @@ final class BugPatternTestExtractorTest {
   }
 
   private static void verifyGeneratedFileContent(
-      Path outputDirectory, String testClass, TestCases expected) {
+      Path outputDirectory, String testClass, BugPatternTestCases expected) {
     assertThat(outputDirectory.resolve(String.format("bugpattern-test-%s.json", testClass)))
         .exists()
-        .returns(expected, path -> Json.read(path, TestCases.class));
+        .returns(expected, path -> Json.read(path, BugPatternTestCases.class));
   }
 }

documentation-support/src/test/java/tech/picnic/errorprone/documentation/DocumentationGeneratorTaskListenerTest.java

@@ -10,7 +10,6 @@ import static org.junit.jupiter.api.condition.OS.WINDOWS;
 import com.google.auto.service.AutoService;
 import com.google.auto.value.AutoValue;
 import com.google.common.collect.ImmutableList;
-import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Sets;
 import com.google.common.collect.Streams;
 import com.google.errorprone.VisitorState;
@@ -41,7 +40,8 @@ final class DocumentationGeneratorTaskListenerTest {
                 entry ->
                     AclEntry.newBuilder(entry)
                         .setPermissions(
-                            Sets.difference(entry.permissions(), ImmutableSet.of(ADD_SUBDIRECTORY)))
+                            Sets.difference(
+                                entry.permissions(), Sets.immutableEnumSet(ADD_SUBDIRECTORY)))
                         .build())
             .collect(toImmutableList()));
 

documentation-support/src/test/java/tech/picnic/errorprone/documentation/RefasterRuleCollectionTestExtractorTest.java

@@ -0,0 +1,166 @@
+package tech.picnic.errorprone.documentation;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import com.google.common.base.VerifyException;
+import com.google.common.collect.ImmutableList;
+import java.net.URI;
+import java.nio.file.Path;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+import tech.picnic.errorprone.documentation.RefasterRuleCollectionTestExtractor.RefasterTestCase;
+import tech.picnic.errorprone.documentation.RefasterRuleCollectionTestExtractor.RefasterTestCases;
+
+final class RefasterRuleCollectionTestExtractorTest {
+  @Test
+  void noRefasterRuleTest(@TempDir Path outputDirectory) {
+    Compilation.compileWithDocumentationGenerator(
+        outputDirectory, "NoRefasterRuleTest.java", "public final class NoRefasterRuleTest {}");
+
+    assertThat(outputDirectory.toAbsolutePath()).isEmptyDirectory();
+  }
+
+  @Test
+  void invalidTestClassName(@TempDir Path outputDirectory) {
+    assertThatThrownBy(
+            () ->
+                Compilation.compileWithDocumentationGenerator(
+                    outputDirectory,
+                    "InvalidTestClassNameInput.java",
+                    "import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;",
+                    "",
+                    "final class InvalidTestClassName implements RefasterRuleCollectionTestCase {}"))
+        .cause()
+        .isInstanceOf(VerifyException.class)
+        .hasMessage(
+            "Refaster rule collection test class name 'InvalidTestClassName' does not match '(.*)Test'");
+  }
+
+  @Test
+  void invalidFileName(@TempDir Path outputDirectory) {
+    assertThatThrownBy(
+            () ->
+                Compilation.compileWithDocumentationGenerator(
+                    outputDirectory,
+                    "InvalidFileNameTest.java",
+                    "import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;",
+                    "",
+                    "final class InvalidFileNameTest implements RefasterRuleCollectionTestCase {}"))
+        .cause()
+        .isInstanceOf(VerifyException.class)
+        .hasMessage(
+            "Refaster rule collection test file name '/InvalidFileNameTest.java' does not match '.*(Input|Output)\\.java'");
+  }
+
+  @Test
+  void emptyRefasterRuleCollectionTestInput(@TempDir Path outputDirectory) {
+    Compilation.compileWithDocumentationGenerator(
+        outputDirectory,
+        "EmptyRefasterRuleCollectionTestInput.java",
+        "import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;",
+        "",
+        "final class EmptyRefasterRuleCollectionTest implements RefasterRuleCollectionTestCase {}");
+
+    verifyGeneratedFileContent(
+        outputDirectory,
+        "EmptyRefasterRuleCollectionTestInput",
+        RefasterTestCases.create(
+            URI.create("file:///EmptyRefasterRuleCollectionTestInput.java"),
+            "EmptyRefasterRuleCollection",
+            /* isInput= */ true,
+            ImmutableList.of()));
+  }
+
+  @Test
+  void singletonRefasterRuleCollectionTestOutput(@TempDir Path outputDirectory) {
+    Compilation.compileWithDocumentationGenerator(
+        outputDirectory,
+        "SingletonRefasterRuleCollectionTestOutput.java",
+        "import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;",
+        "",
+        "final class SingletonRefasterRuleCollectionTest implements RefasterRuleCollectionTestCase {",
+        "  int testMyRule() {",
+        "    return 42;",
+        "  }",
+        "}");
+
+    verifyGeneratedFileContent(
+        outputDirectory,
+        "SingletonRefasterRuleCollectionTestOutput",
+        RefasterTestCases.create(
+            URI.create("file:///SingletonRefasterRuleCollectionTestOutput.java"),
+            "SingletonRefasterRuleCollection",
+            /* isInput= */ false,
+            ImmutableList.of(
+                RefasterTestCase.create(
+                    "MyRule",
+                    """
+                    int testMyRule() {
+                      return 42;
+                    }"""))));
+  }
+
+  @Test
+  void complexRefasterRuleCollectionTestOutput(@TempDir Path outputDirectory) {
+    Compilation.compileWithDocumentationGenerator(
+        outputDirectory,
+        "pkg/ComplexRefasterRuleCollectionTestInput.java",
+        "package pkg;",
+        "",
+        "import com.google.common.collect.ImmutableSet;",
+        "import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;",
+        "",
+        "final class ComplexRefasterRuleCollectionTest implements RefasterRuleCollectionTestCase {",
+        "  private static final String IGNORED_CONSTANT = \"constant\";",
+        "",
+        "  @Override",
+        "  public ImmutableSet<Object> elidedTypesAndStaticImports() {",
+        "    return ImmutableSet.of();",
+        "  }",
+        "",
+        "  /** Javadoc. */",
+        "  String testFirstRule() {",
+        "    return \"Don't panic\";",
+        "  }",
+        "",
+        "  // Comment.",
+        "  String testSecondRule() {",
+        "    return \"Carry a towel\";",
+        "  }",
+        "",
+        "  void testEmptyRule() {}",
+        "}");
+
+    verifyGeneratedFileContent(
+        outputDirectory,
+        "ComplexRefasterRuleCollectionTestInput",
+        RefasterTestCases.create(
+            URI.create("file:///pkg/ComplexRefasterRuleCollectionTestInput.java"),
+            "ComplexRefasterRuleCollection",
+            /* isInput= */ true,
+            ImmutableList.of(
+                RefasterTestCase.create(
+                    "FirstRule",
+                    """
+                    String testFirstRule() {
+                      return "Don't panic";
+                    }"""),
+                RefasterTestCase.create(
+                    "SecondRule",
+                    """
+                    String testSecondRule() {
+                      return "Carry a towel";
+                    }"""),
+                RefasterTestCase.create("EmptyRule", "void testEmptyRule() {}"))));
+  }
+
+  private static void verifyGeneratedFileContent(
+      Path outputDirectory, String testIdentifier, RefasterTestCases expected) {
+    assertThat(
+            outputDirectory.resolve(
+                String.format("refaster-rule-collection-test-%s.json", testIdentifier)))
+        .exists()
+        .returns(expected, path -> Json.read(path, RefasterTestCases.class));
+  }
+}

error-prone-contrib/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.17.0</version>
+        <version>0.19.2-SNAPSHOT</version>
     </parent>
 
     <artifactId>error-prone-contrib</artifactId>
@@ -55,7 +55,12 @@
         <dependency>
             <groupId>${project.groupId}</groupId>
             <artifactId>refaster-support</artifactId>
-            <scope>provided</scope>
+            <!-- XXX: One would expect this to be a `provided` dependency (as
+            Refaster rules are interpreted by the `refaster-runner` module),
+            but the `OptionalOrElseGet` bug checker defined by this module
+            depends on the `RequiresComputation` matcher that
+            `refaster-support` primarily exposes for use by Refaster rules.
+            Review this setup. (Should the matchers be moved elsewhere?) -->
         </dependency>
         <dependency>
             <groupId>${project.groupId}</groupId>
@@ -67,6 +72,11 @@
             <artifactId>jackson-annotations</artifactId>
             <scope>provided</scope>
         </dependency>
+        <dependency>
+            <groupId>com.github.ben-manes.caffeine</groupId>
+            <artifactId>caffeine</artifactId>
+            <scope>provided</scope>
+        </dependency>
         <dependency>
             <groupId>com.google.auto.service</groupId>
             <artifactId>auto-service-annotations</artifactId>
@@ -82,6 +92,11 @@
             <artifactId>guava</artifactId>
             <scope>provided</scope>
         </dependency>
+        <dependency>
+            <groupId>io.micrometer</groupId>
+            <artifactId>micrometer-core</artifactId>
+            <scope>provided</scope>
+        </dependency>
         <dependency>
             <groupId>io.projectreactor</groupId>
             <artifactId>reactor-core</artifactId>
@@ -196,7 +211,7 @@
         </dependency>
         <dependency>
             <groupId>org.openrewrite</groupId>
-            <artifactId>rewrite-java-11</artifactId>
+            <artifactId>rewrite-java-17</artifactId>
             <scope>test</scope>
         </dependency>
         <dependency>
@@ -287,6 +302,55 @@
                             <arg>-Xplugin:DocumentationGenerator -XoutputDirectory=${project.build.directory}/docs</arg>
                         </compilerArgs>
                     </configuration>
+                    <executions>
+                        <!-- The Refaster input/output test classes used by
+                        `RefasterRuleCollection` are modelled as classpath
+                        resources, and thus not subject to the default test
+                        compilation step. These two custom compilation steps
+                        serve two purposes:
+                        - To provide early feedback in case of syntax errors.
+                        - To enable the `DocumentationGenerator` compiler
+                        plugin to extract documentation metadata from them.
+                        Note that the input and output files must be compiled
+                        separately and to distinct output directories, as they
+                        define the same set of class names. -->
+                        <!-- XXX: Drop these executions if/when the Refaster
+                        test framework is reimplemented such that tests can be
+                        located alongside rules, rather than in two additional
+                        resource files. -->
+                        <execution>
+                            <id>compile-refaster-test-input</id>
+                            <goals>
+                                <goal>testCompile</goal>
+                            </goals>
+                            <phase>process-test-resources</phase>
+                            <configuration>
+                                <compileSourceRoots>
+                                    <compileSourceRoot>${project.basedir}/src/test/resources</compileSourceRoot>
+                                </compileSourceRoots>
+                                <testIncludes>
+                                    <testInclude>**/*Input.java</testInclude>
+                                </testIncludes>
+                                <outputDirectory>${project.build.directory}/refaster-test-input</outputDirectory>
+                            </configuration>
+                        </execution>
+                        <execution>
+                            <id>compile-refaster-test-output</id>
+                            <goals>
+                                <goal>testCompile</goal>
+                            </goals>
+                            <phase>process-test-resources</phase>
+                            <configuration>
+                                <compileSourceRoots>
+                                    <compileSourceRoot>${project.basedir}/src/test/resources</compileSourceRoot>
+                                </compileSourceRoots>
+                                <testIncludes>
+                                    <testInclude>**/*Output.java</testInclude>
+                                </testIncludes>
+                                <outputDirectory>${project.build.directory}/refaster-test-output</outputDirectory>
+                            </configuration>
+                        </execution>
+                    </executions>
                 </plugin>
             </plugins>
         </pluginManagement>

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

@@ -3,6 +3,7 @@ package tech.picnic.errorprone.bugpatterns;
 import static com.google.errorprone.BugPattern.LinkType.CUSTOM;
 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 tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
@@ -19,7 +20,6 @@ import com.sun.source.tree.AnnotationTree;
 import com.sun.source.tree.AssignmentTree;
 import com.sun.source.tree.ExpressionTree;
 import com.sun.source.tree.NewArrayTree;
-import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
 import java.util.function.BiFunction;
@@ -38,12 +38,11 @@ import tech.picnic.errorprone.utils.SourceCode;
 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(
-              CanonicalAnnotationSyntax::dropRedundantParentheses,
-              CanonicalAnnotationSyntax::dropRedundantValueAttribute,
-              CanonicalAnnotationSyntax::dropRedundantCurlies);
+  private static final ImmutableSet<BiFunction<AnnotationTree, VisitorState, Fix>> FIX_FACTORIES =
+      ImmutableSet.of(
+          CanonicalAnnotationSyntax::dropRedundantParentheses,
+          CanonicalAnnotationSyntax::dropRedundantValueAttribute,
+          CanonicalAnnotationSyntax::dropRedundantCurlies);
 
   /** Instantiates a new {@link CanonicalAnnotationSyntax} instance. */
   public CanonicalAnnotationSyntax() {}
@@ -52,39 +51,38 @@ public final class CanonicalAnnotationSyntax extends BugChecker implements Annot
   public Description matchAnnotation(AnnotationTree tree, VisitorState state) {
     return FIX_FACTORIES.stream()
         .map(op -> op.apply(tree, state))
-        .flatMap(Optional::stream)
+        .filter(not(Fix::isEmpty))
         .findFirst()
         .map(fix -> describeMatch(tree, fix))
         .orElse(Description.NO_MATCH);
   }
 
-  private static Optional<Fix> dropRedundantParentheses(AnnotationTree tree, VisitorState state) {
+  private static Fix dropRedundantParentheses(AnnotationTree tree, VisitorState state) {
     if (!tree.getArguments().isEmpty()) {
       /* Parentheses are necessary. */
-      return Optional.empty();
+      return SuggestedFix.emptyFix();
     }
 
     String src = state.getSourceForNode(tree);
     if (src == null) {
       /* Without the source code there's not much we can do. */
-      return Optional.empty();
+      return SuggestedFix.emptyFix();
     }
 
     int parenIndex = src.indexOf('(');
     if (parenIndex < 0) {
       /* There are no redundant parentheses. */
-      return Optional.empty();
+      return SuggestedFix.emptyFix();
     }
 
-    return Optional.of(SuggestedFix.replace(tree, src.substring(0, parenIndex)));
+    return SuggestedFix.replace(tree, src.substring(0, parenIndex));
   }
 
-  private static Optional<Fix> dropRedundantValueAttribute(
-      AnnotationTree tree, VisitorState state) {
+  private static Fix dropRedundantValueAttribute(AnnotationTree tree, VisitorState state) {
     List<? extends ExpressionTree> args = tree.getArguments();
     if (args.size() != 1) {
       /* The `value` attribute, if specified, cannot be dropped. */
-      return Optional.empty();
+      return SuggestedFix.emptyFix();
     }
 
     ExpressionTree arg = args.get(0);
@@ -93,25 +91,23 @@ public final class CanonicalAnnotationSyntax extends BugChecker implements Annot
        * The annotation argument doesn't have a source representation, e.g. because `value` isn't
        * assigned explicitly.
        */
-      return Optional.empty();
+      return SuggestedFix.emptyFix();
     }
 
     ExpressionTree expr = AnnotationMatcherUtils.getArgument(tree, "value");
     if (expr == null) {
       /* This is not an explicit assignment to the `value` attribute. */
-      return Optional.empty();
+      return SuggestedFix.emptyFix();
     }
 
     /* Replace the assignment with (the simplified representation of) just its value. */
-    return Optional.of(
-        SuggestedFix.replace(
-            arg,
-            simplifyAttributeValue(expr, state)
-                .orElseGet(() -> SourceCode.treeToString(expr, state))));
+    return SuggestedFix.replace(
+        arg,
+        simplifyAttributeValue(expr, state).orElseGet(() -> SourceCode.treeToString(expr, state)));
   }
 
-  private static Optional<Fix> dropRedundantCurlies(AnnotationTree tree, VisitorState state) {
-    List<SuggestedFix.Builder> fixes = new ArrayList<>();
+  private static Fix dropRedundantCurlies(AnnotationTree tree, VisitorState state) {
+    SuggestedFix.Builder fix = SuggestedFix.builder();
     for (ExpressionTree arg : tree.getArguments()) {
       /*
        * We'll try to simplify each assignment's RHS; for non-assignment we'll try to simplify
@@ -122,10 +118,10 @@ public final class CanonicalAnnotationSyntax extends BugChecker implements Annot
 
       /* Store a fix for each expression that was successfully simplified. */
       simplifyAttributeValue(value, state)
-          .ifPresent(expr -> fixes.add(SuggestedFix.builder().replace(value, expr)));
+          .ifPresent(expr -> fix.merge(SuggestedFix.replace(value, expr)));
     }
 
-    return fixes.stream().reduce(SuggestedFix.Builder::merge).map(SuggestedFix.Builder::build);
+    return fix.build();
   }
 
   private static Optional<String> simplifyAttributeValue(ExpressionTree expr, VisitorState state) {

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

@@ -0,0 +1,72 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.CUSTOM;
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
+
+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.LambdaExpressionTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.util.ASTHelpers;
+import com.sun.source.tree.LambdaExpressionTree;
+import com.sun.source.tree.TypeCastTree;
+import com.sun.source.tree.VariableTree;
+import com.sun.tools.javac.code.Type;
+import tech.picnic.errorprone.utils.SourceCode;
+
+/**
+ * A {@link BugChecker} that flags lambda expressions that can be replaced with a method reference
+ * of the form {@code T.class::cast}.
+ */
+// XXX: Consider folding this logic into the `MethodReferenceUsage` check of the
+// `error-prone-experimental` module.
+// XXX: This check and its tests are structurally nearly identical to `IsInstanceLambdaUsage`.
+// Unless folded into `MethodReferenceUsage`, consider merging the two.
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "Prefer `Class::cast` method reference over equivalent lambda expression",
+    link = BUG_PATTERNS_BASE_URL + "ClassCastLambdaUsage",
+    linkType = CUSTOM,
+    severity = SUGGESTION,
+    tags = SIMPLIFICATION)
+public final class ClassCastLambdaUsage extends BugChecker implements LambdaExpressionTreeMatcher {
+  private static final long serialVersionUID = 1L;
+
+  /** Instantiates a new {@link ClassCastLambdaUsage} instance. */
+  public ClassCastLambdaUsage() {}
+
+  @Override
+  public Description matchLambdaExpression(LambdaExpressionTree tree, VisitorState state) {
+    if (tree.getParameters().size() != 1 || !(tree.getBody() instanceof TypeCastTree typeCast)) {
+      return Description.NO_MATCH;
+    }
+
+    Type type = ASTHelpers.getType(typeCast);
+    if (type == null || type.isParameterized() || type.isPrimitive()) {
+      /*
+       * The method reference syntax does not support casting to parameterized types. Additionally,
+       * `Class#cast` does not support the same range of type conversions between (boxed) primitive
+       * types as the cast operator.
+       */
+      // XXX: Depending on the declared type of the value being cast, in some cases we _can_ rewrite
+      // primitive casts. Add support for this.
+      return Description.NO_MATCH;
+    }
+
+    VariableTree param = Iterables.getOnlyElement(tree.getParameters());
+    if (!ASTHelpers.getSymbol(param).equals(ASTHelpers.getSymbol(typeCast.getExpression()))) {
+      return Description.NO_MATCH;
+    }
+
+    return describeMatch(
+        tree,
+        SuggestedFix.replace(
+            tree, SourceCode.treeToString(typeCast.getType(), state) + ".class::cast"));
+  }
+}

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

@@ -0,0 +1,125 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.CUSTOM;
+import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
+import static com.google.errorprone.BugPattern.StandardTags.STYLE;
+import static com.google.errorprone.matchers.Matchers.allOf;
+import static com.google.errorprone.matchers.Matchers.hasModifier;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
+
+import com.google.auto.service.AutoService;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Sets;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.ErrorProneFlags;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.VariableTreeMatcher;
+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.sun.source.tree.VariableTree;
+import com.sun.source.util.TreeScanner;
+import java.util.Locale;
+import java.util.regex.Pattern;
+import javax.inject.Inject;
+import javax.lang.model.element.Modifier;
+import org.jspecify.annotations.Nullable;
+import tech.picnic.errorprone.utils.Flags;
+
+/**
+ * A {@link BugChecker} that flags static constants that do not follow the upper snake case naming
+ * convention.
+ */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "Constant variables should adhere to the `UPPER_SNAKE_CASE` naming convention",
+    link = BUG_PATTERNS_BASE_URL + "ConstantNaming",
+    linkType = CUSTOM,
+    severity = WARNING,
+    tags = STYLE)
+@SuppressWarnings("java:S2160" /* Super class equality definition suffices. */)
+public final class ConstantNaming extends BugChecker implements VariableTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Matcher<VariableTree> IS_CONSTANT =
+      allOf(hasModifier(Modifier.STATIC), hasModifier(Modifier.FINAL));
+  private static final Matcher<VariableTree> IS_PRIVATE = hasModifier(Modifier.PRIVATE);
+  private static final Pattern SNAKE_CASE = Pattern.compile("([a-z])([A-Z])");
+  private static final ImmutableSet<String> DEFAULT_EXEMPTED_NAMES =
+      ImmutableSet.of("serialVersionUID");
+
+  /**
+   * Flag using which constant names that must not be flagged (in addition to those defined by
+   * {@link #DEFAULT_EXEMPTED_NAMES}) can be specified.
+   */
+  private static final String ADDITIONAL_EXEMPTED_NAMES_FLAG =
+      "CanonicalConstantNaming:ExemptedNames";
+
+  private final ImmutableSet<String> exemptedNames;
+
+  /** Instantiates a default {@link ConstantNaming} instance. */
+  public ConstantNaming() {
+    this(ErrorProneFlags.empty());
+  }
+
+  /**
+   * Instantiates a customized {@link ConstantNaming}.
+   *
+   * @param flags Any provided command line flags.
+   */
+  @Inject
+  ConstantNaming(ErrorProneFlags flags) {
+    exemptedNames =
+        Sets.union(DEFAULT_EXEMPTED_NAMES, Flags.getSet(flags, ADDITIONAL_EXEMPTED_NAMES_FLAG))
+            .immutableCopy();
+  }
+
+  @Override
+  public Description matchVariable(VariableTree tree, VisitorState state) {
+    String variableName = tree.getName().toString();
+    if (!IS_CONSTANT.matches(tree, state) || exemptedNames.contains(variableName)) {
+      return Description.NO_MATCH;
+    }
+
+    String replacement = toUpperSnakeCase(variableName);
+    if (replacement.equals(variableName)) {
+      return Description.NO_MATCH;
+    }
+
+    Description.Builder description = buildDescription(tree);
+    if (!IS_PRIVATE.matches(tree, state)) {
+      description.setMessage(
+          "%s; consider renaming to '%s', though note that this is not a private constant"
+              .formatted(message(), replacement));
+    } else if (isVariableNameInUse(replacement, state)) {
+      description.setMessage(
+          "%s; consider renaming to '%s', though note that a variable with this name is already declared"
+              .formatted(message(), replacement));
+    } else {
+      description.addFix(SuggestedFixes.renameVariable(tree, replacement, state));
+    }
+
+    return description.build();
+  }
+
+  private static String toUpperSnakeCase(String variableName) {
+    return SNAKE_CASE.matcher(variableName).replaceAll("$1_$2").toUpperCase(Locale.ROOT);
+  }
+
+  private static boolean isVariableNameInUse(String name, VisitorState state) {
+    return Boolean.TRUE.equals(
+        new TreeScanner<Boolean, @Nullable Void>() {
+          @Override
+          public Boolean visitVariable(VariableTree tree, @Nullable Void unused) {
+            return ASTHelpers.getSymbol(tree).getSimpleName().contentEquals(name)
+                || super.visitVariable(tree, null);
+          }
+
+          @Override
+          public Boolean reduce(Boolean r1, Boolean r2) {
+            return Boolean.TRUE.equals(r1) || Boolean.TRUE.equals(r2);
+          }
+        }.scan(state.getPath().getCompilationUnit(), null));
+  }
+}

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

@@ -62,7 +62,7 @@ public final class EmptyMethod extends BugChecker implements MethodTreeMatcher {
   }
 
   private static boolean isInPossibleTestHelperClass(VisitorState state) {
-    return Optional.ofNullable(ASTHelpers.findEnclosingNode(state.getPath(), ClassTree.class))
+    return Optional.ofNullable(state.findEnclosing(ClassTree.class))
         .map(ClassTree::getSimpleName)
         .filter(name -> name.toString().contains("Test"))
         .isPresent();

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

@@ -36,6 +36,7 @@ import java.util.Formatter;
 import java.util.List;
 import java.util.Optional;
 import org.jspecify.annotations.Nullable;
+import tech.picnic.errorprone.utils.MoreASTHelpers;
 import tech.picnic.errorprone.utils.SourceCode;
 
 /**
@@ -203,14 +204,10 @@ public final class FormatStringConcatenation extends BugChecker
 
     ExpressionTree argument = ASTHelpers.stripParentheses(arguments.get(argPosition));
     return argument instanceof BinaryTree
-        && isStringTyped(argument, state)
+        && MoreASTHelpers.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<@Nullable Void, VisitorState> {
     private final StringBuilder formatString = new StringBuilder();
@@ -223,7 +220,7 @@ public final class FormatStringConcatenation extends BugChecker
 
     @Override
     public @Nullable Void visitBinary(BinaryTree tree, VisitorState state) {
-      if (tree.getKind() == Kind.PLUS && isStringTyped(tree, state)) {
+      if (tree.getKind() == Kind.PLUS && MoreASTHelpers.isStringTyped(tree, state)) {
         tree.getLeftOperand().accept(this, state);
         tree.getRightOperand().accept(this, state);
       } else {

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

@@ -39,6 +39,7 @@ import com.sun.source.tree.MemberSelectTree;
 import com.sun.source.tree.MethodInvocationTree;
 import com.sun.tools.javac.code.Type;
 import com.sun.tools.javac.code.Types;
+import java.time.Instant;
 import java.util.Arrays;
 import java.util.List;
 import tech.picnic.errorprone.utils.SourceCode;
@@ -51,6 +52,7 @@ import tech.picnic.errorprone.utils.SourceCode;
 // is effectively the identity operation.
 // XXX: Also flag nullary instance method invocations that represent an identity conversion, such as
 // `Boolean#booleanValue()`, `Byte#byteValue()` and friends.
+// XXX: Also flag redundant round-trip conversions such as `path.toFile().toPath()`.
 @AutoService(BugChecker.class)
 @BugPattern(
     summary = "Avoid or clarify identity conversions",
@@ -83,6 +85,7 @@ public final class IdentityConversion extends BugChecker implements MethodInvoca
                   ImmutableSetMultimap.class.getCanonicalName(),
                   ImmutableTable.class.getCanonicalName())
               .named("copyOf"),
+          staticMethod().onClass(Instant.class.getCanonicalName()).namedAnyOf("from"),
           staticMethod().onClass(Matchers.class.getCanonicalName()).namedAnyOf("allOf", "anyOf"),
           staticMethod().onClass("reactor.adapter.rxjava.RxJava2Adapter"),
           staticMethod()

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

@@ -25,6 +25,8 @@ import tech.picnic.errorprone.utils.SourceCode;
  */
 // XXX: Consider folding this logic into the `MethodReferenceUsage` check of the
 // `error-prone-experimental` module.
+// XXX: This check and its tests are structurally nearly identical to `ClassCastLambdaUsage`. Unless
+// folded into `MethodReferenceUsage`, consider merging the two.
 @AutoService(BugChecker.class)
 @BugPattern(
     summary = "Prefer `Class::isInstance` method reference over equivalent lambda expression",

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

@@ -16,7 +16,7 @@ import static tech.picnic.errorprone.utils.MoreJUnitMatchers.TEST_METHOD;
 import static tech.picnic.errorprone.utils.MoreMatchers.hasMetaAnnotation;
 
 import com.google.auto.service.AutoService;
-import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Sets;
 import com.google.errorprone.BugPattern;
 import com.google.errorprone.VisitorState;
 import com.google.errorprone.bugpatterns.BugChecker;
@@ -70,7 +70,7 @@ public final class JUnitClassModifiers extends BugChecker implements ClassTreeMa
     SuggestedFixes.removeModifiers(
             tree.getModifiers(),
             state,
-            ImmutableSet.of(Modifier.PRIVATE, Modifier.PROTECTED, Modifier.PUBLIC))
+            Sets.immutableEnumSet(Modifier.PRIVATE, Modifier.PROTECTED, Modifier.PUBLIC))
         .ifPresent(fixBuilder::merge);
 
     if (!HAS_SPRING_CONFIGURATION_ANNOTATION.matches(tree, state)) {

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

@@ -14,6 +14,7 @@ import com.google.common.base.Splitter;
 import com.google.common.collect.Comparators;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Sets;
 import com.google.errorprone.BugPattern;
 import com.google.errorprone.ErrorProneFlags;
 import com.google.errorprone.VisitorState;
@@ -34,10 +35,8 @@ import com.sun.source.tree.Tree;
 import com.sun.source.util.TreeScanner;
 import com.sun.tools.javac.code.Symtab;
 import com.sun.tools.javac.code.Type;
-import java.util.HashSet;
 import java.util.List;
 import java.util.Optional;
-import java.util.Set;
 import java.util.stream.Stream;
 import javax.inject.Inject;
 import org.jspecify.annotations.Nullable;
@@ -106,22 +105,19 @@ public final class LexicographicalAnnotationAttributeListing extends BugChecker
 
   @Override
   public Description matchAnnotation(AnnotationTree tree, VisitorState state) {
-    return sortArrayElements(tree, state)
-        .map(fix -> describeMatch(tree, fix))
-        .orElse(Description.NO_MATCH);
+    Fix fix = sortArrayElements(tree, state);
+    return fix.isEmpty() ? Description.NO_MATCH : describeMatch(tree, fix);
   }
 
-  private Optional<Fix> sortArrayElements(AnnotationTree tree, VisitorState state) {
+  private Fix sortArrayElements(AnnotationTree tree, VisitorState state) {
     /*
      * We loop over the array's attributes, trying to sort each array associated with a
      * non-blacklisted attribute. A single compound fix, if any, is returned.
      */
     return matcher
         .extractMatchingArguments(tree)
-        .map(expr -> extractArray(expr).flatMap(arr -> suggestSorting(arr, state)))
-        .flatMap(Optional::stream)
-        .reduce(SuggestedFix.Builder::merge)
-        .map(SuggestedFix.Builder::build);
+        .flatMap(expr -> extractArray(expr).map(arr -> suggestSorting(arr, state)).stream())
+        .collect(SuggestedFix.mergeFixes());
   }
 
   private static Optional<NewArrayTree> extractArray(ExpressionTree expr) {
@@ -130,18 +126,17 @@ public final class LexicographicalAnnotationAttributeListing extends BugChecker
         : Optional.of(expr).filter(NewArrayTree.class::isInstance).map(NewArrayTree.class::cast);
   }
 
-  private static Optional<SuggestedFix.Builder> suggestSorting(
-      NewArrayTree array, VisitorState state) {
+  private static SuggestedFix suggestSorting(NewArrayTree array, VisitorState state) {
     if (array.getInitializers().size() < 2 || !canSort(array, state)) {
       /* There's nothing to sort, or we don't want to sort. */
-      return Optional.empty();
+      return SuggestedFix.emptyFix();
     }
 
     List<? extends ExpressionTree> actualOrdering = array.getInitializers();
     ImmutableList<? extends ExpressionTree> desiredOrdering = doSort(actualOrdering);
     if (actualOrdering.equals(desiredOrdering)) {
       /* In the (presumably) common case the elements are already sorted. */
-      return Optional.empty();
+      return SuggestedFix.emptyFix();
     }
 
     /* The elements aren't sorted. Suggest the sorted alternative. */
@@ -149,7 +144,7 @@ public final class LexicographicalAnnotationAttributeListing extends BugChecker
         desiredOrdering.stream()
             .map(expr -> SourceCode.treeToString(expr, state))
             .collect(joining(", ", "{", "}"));
-    return Optional.of(SuggestedFix.builder().replace(array, suggestion));
+    return SuggestedFix.replace(array, suggestion);
   }
 
   private static boolean canSort(Tree array, VisitorState state) {
@@ -163,7 +158,12 @@ public final class LexicographicalAnnotationAttributeListing extends BugChecker
 
     /* For now we don't force sorting on numeric types. */
     return Stream.of(
-            symtab.annotationType, symtab.classType, symtab.enumSym.type, symtab.stringType)
+            symtab.annotationType,
+            symtab.booleanType,
+            symtab.charType,
+            symtab.classType,
+            symtab.enumSym.type,
+            symtab.stringType)
         .anyMatch(t -> ASTHelpers.isSubtype(elemType, t, state));
   }
 
@@ -225,10 +225,8 @@ public final class LexicographicalAnnotationAttributeListing extends BugChecker
         excludedAnnotations(flags));
   }
 
-  private static ImmutableList<String> excludedAnnotations(ErrorProneFlags flags) {
-    Set<String> exclusions = new HashSet<>();
-    exclusions.addAll(Flags.getList(flags, EXCLUDED_ANNOTATIONS_FLAG));
-    exclusions.addAll(BLACKLISTED_ANNOTATIONS);
-    return ImmutableList.copyOf(exclusions);
+  private static ImmutableSet<String> excludedAnnotations(ErrorProneFlags flags) {
+    return Sets.union(BLACKLISTED_ANNOTATIONS, Flags.getSet(flags, EXCLUDED_ANNOTATIONS_FLAG))
+        .immutableCopy();
   }
 }

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

@@ -10,7 +10,6 @@ import static java.util.Comparator.comparing;
 import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
-import com.google.common.base.VerifyException;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Streams;
 import com.google.errorprone.BugPattern;
@@ -105,10 +104,7 @@ public final class LexicographicalAnnotationListing extends BugChecker
             originalAnnotations.stream(),
             sortedAnnotations.stream(),
             (original, replacement) ->
-                SuggestedFix.builder()
-                    .replace(original, SourceCode.treeToString(replacement, state)))
-        .reduce(SuggestedFix.Builder::merge)
-        .map(SuggestedFix.Builder::build)
-        .orElseThrow(() -> new VerifyException("No annotations were provided"));
+                SuggestedFix.replace(original, SourceCode.treeToString(replacement, state)))
+        .collect(SuggestedFix.mergeFixes());
   }
 }

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

@@ -18,14 +18,12 @@ import com.google.errorprone.fixes.SuggestedFixes;
 import com.google.errorprone.matchers.Description;
 import com.google.errorprone.matchers.Matcher;
 import com.google.errorprone.refaster.Refaster;
-import com.google.errorprone.util.ASTHelpers;
 import com.sun.source.tree.ExpressionTree;
-import com.sun.source.tree.IdentifierTree;
-import com.sun.source.tree.LiteralTree;
 import com.sun.source.tree.MemberSelectTree;
 import com.sun.source.tree.MethodInvocationTree;
 import java.util.Optional;
 import java.util.function.Supplier;
+import tech.picnic.errorprone.refaster.matchers.RequiresComputation;
 import tech.picnic.errorprone.utils.SourceCode;
 
 /**
@@ -36,12 +34,12 @@ import tech.picnic.errorprone.utils.SourceCode;
  * it does, the suggested fix changes the program's semantics. Such fragile code must instead be
  * refactored such that the side-effectful code does not appear accidental.
  */
-// XXX: Consider also implementing the inverse, in which `.orElseGet(() -> someConstant)` is
-// flagged.
-// XXX: Once the `MethodReferenceUsageCheck` becomes generally usable, consider leaving the method
-// reference cleanup to that check, and express the remainder of the logic in this class using a
-// Refaster template, i.c.w. a `@Matches` constraint that implements the `requiresComputation`
-// logic.
+// XXX: This rule may introduce a compilation error: the `value` expression may reference a
+// non-effectively final variable, which is not allowed in the replacement lambda expression.
+// Review whether a `@Matcher` can be used to avoid this.
+// XXX: Once the `MethodReferenceUsageCheck` bug checker becomes generally usable, consider leaving
+// the method reference cleanup to that check, and express the remainder of the logic in this class
+// using a Refaster template, i.c.w. a `@NotMatches(RequiresComputation.class)` constraint.
 @AutoService(BugChecker.class)
 @BugPattern(
     summary =
@@ -51,16 +49,17 @@ import tech.picnic.errorprone.utils.SourceCode;
     linkType = NONE,
     severity = WARNING,
     tags = PERFORMANCE)
-public final class OptionalOrElse extends BugChecker implements MethodInvocationTreeMatcher {
+public final class OptionalOrElseGet extends BugChecker implements MethodInvocationTreeMatcher {
   private static final long serialVersionUID = 1L;
+  private static final Matcher<ExpressionTree> REQUIRES_COMPUTATION = new RequiresComputation();
   private static final Matcher<ExpressionTree> OPTIONAL_OR_ELSE_METHOD =
       instanceMethod().onExactClass(Optional.class.getCanonicalName()).namedAnyOf("orElse");
   // XXX: Also exclude invocations of `@Placeholder`-annotated methods.
   private static final Matcher<ExpressionTree> REFASTER_METHOD =
       staticMethod().onClass(Refaster.class.getCanonicalName());
 
-  /** Instantiates a new {@link OptionalOrElse} instance. */
-  public OptionalOrElse() {}
+  /** Instantiates a new {@link OptionalOrElseGet} instance. */
+  public OptionalOrElseGet() {}
 
   @Override
   public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
@@ -69,7 +68,8 @@ public final class OptionalOrElse extends BugChecker implements MethodInvocation
     }
 
     ExpressionTree argument = Iterables.getOnlyElement(tree.getArguments());
-    if (!requiresComputation(argument) || REFASTER_METHOD.matches(argument, state)) {
+    if (!REQUIRES_COMPUTATION.matches(argument, state)
+        || REFASTER_METHOD.matches(argument, state)) {
       return Description.NO_MATCH;
     }
 
@@ -91,18 +91,6 @@ public final class OptionalOrElse extends BugChecker implements MethodInvocation
     return describeMatch(tree, fix);
   }
 
-  /**
-   * Tells whether the given expression contains anything other than a literal or a (possibly
-   * dereferenced) variable or constant.
-   */
-  private static boolean requiresComputation(ExpressionTree tree) {
-    return !(tree instanceof IdentifierTree
-        || tree instanceof LiteralTree
-        || (tree instanceof MemberSelectTree memberSelect
-            && !requiresComputation(memberSelect.getExpression()))
-        || ASTHelpers.constValue(tree) != null);
-  }
-
   /** Returns the nullary method reference matching the given expression, if any. */
   private static Optional<String> tryMethodReferenceConversion(
       ExpressionTree tree, VisitorState state) {
@@ -118,7 +106,7 @@ public final class OptionalOrElse extends BugChecker implements MethodInvocation
       return Optional.empty();
     }
 
-    if (requiresComputation(memberSelect.getExpression())) {
+    if (REQUIRES_COMPUTATION.matches(memberSelect.getExpression(), state)) {
       return Optional.empty();
     }
 

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

@@ -6,6 +6,7 @@ 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 static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
@@ -85,22 +86,22 @@ public final class PrimitiveComparison extends BugChecker implements MethodInvoc
     }
 
     return getPotentiallyBoxedReturnType(tree.getArguments().get(0))
-        .flatMap(cmpType -> attemptMethodInvocationReplacement(tree, cmpType, isStatic, state))
+        .map(cmpType -> attemptMethodInvocationReplacement(tree, cmpType, isStatic, state))
+        .filter(not(SuggestedFix::isEmpty))
         .map(fix -> describeMatch(tree, fix))
         .orElse(Description.NO_MATCH);
   }
 
-  private static Optional<Fix> attemptMethodInvocationReplacement(
+  private static SuggestedFix 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 SuggestedFix.emptyFix();
     }
 
-    return Optional.of(
-        suggestFix(
-            tree, prefixTypeArgumentsIfRelevant(preferredMethodName, tree, cmpType, state), state));
+    return suggestFix(
+        tree, prefixTypeArgumentsIfRelevant(preferredMethodName, tree, cmpType, state), state);
   }
 
   /**
@@ -169,7 +170,7 @@ public final class PrimitiveComparison extends BugChecker implements MethodInvoc
   }
 
   // XXX: Use switch pattern matching once the targeted JDK supports this.
-  private static Fix suggestFix(
+  private static SuggestedFix suggestFix(
       MethodInvocationTree tree, String preferredMethodName, VisitorState state) {
     ExpressionTree expr = tree.getMethodSelect();
 

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

@@ -44,7 +44,6 @@ import com.sun.source.tree.Tree.Kind;
 import java.io.Console;
 import java.io.PrintStream;
 import java.io.PrintWriter;
-import java.util.ArrayList;
 import java.util.Formattable;
 import java.util.Formatter;
 import java.util.List;
@@ -177,18 +176,18 @@ public final class RedundantStringConversion extends BugChecker
       return createDescription(tree, tryFix(rhs, state, STRING));
     }
 
-    List<SuggestedFix.Builder> fixes = new ArrayList<>();
+    SuggestedFix.Builder fix = SuggestedFix.builder();
 
     // XXX: Avoid trying to simplify the RHS twice.
     ExpressionTree preferredRhs = trySimplify(rhs, state).orElse(rhs);
     if (STRING.matches(preferredRhs, state)) {
-      tryFix(lhs, state, ANY_EXPR).ifPresent(fixes::add);
+      fix.merge(tryFix(lhs, state, ANY_EXPR));
     } else {
-      tryFix(lhs, state, STRING).ifPresent(fixes::add);
+      fix.merge(tryFix(lhs, state, STRING));
     }
-    tryFix(rhs, state, ANY_EXPR).ifPresent(fixes::add);
+    fix.merge(tryFix(rhs, state, ANY_EXPR));
 
-    return createDescription(tree, fixes.stream().reduce(SuggestedFix.Builder::merge));
+    return createDescription(tree, fix.build());
   }
 
   @Override
@@ -229,17 +228,18 @@ public final class RedundantStringConversion extends BugChecker
     return createDescription(tree, tryFix(tree, state, NON_NULL_STRING));
   }
 
-  private Optional<SuggestedFix.Builder> tryFixPositionalConverter(
+  private SuggestedFix tryFixPositionalConverter(
       List<? extends ExpressionTree> arguments, VisitorState state, int index) {
     return Optional.of(arguments)
         .filter(args -> args.size() > index)
-        .flatMap(args -> tryFix(args.get(index), state, ANY_EXPR));
+        .map(args -> tryFix(args.get(index), state, ANY_EXPR))
+        .orElseGet(SuggestedFix::emptyFix);
   }
 
   // XXX: Write another check that checks that Formatter patterns don't use `{}` and have a
   // matching number of arguments of the appropriate type. Also flag explicit conversions from
   // `Formattable` to string.
-  private Optional<SuggestedFix.Builder> tryFixFormatter(
+  private SuggestedFix tryFixFormatter(
       List<? extends ExpressionTree> arguments, VisitorState state) {
     /*
      * Formatter methods have an optional first `Locale` parameter; if present, it must be
@@ -258,7 +258,7 @@ public final class RedundantStringConversion extends BugChecker
     return tryFixFormatterArguments(arguments, state, LOCALE, NOT_FORMATTABLE);
   }
 
-  private Optional<SuggestedFix.Builder> tryFixGuavaGuard(
+  private SuggestedFix tryFixGuavaGuard(
       List<? extends ExpressionTree> arguments, VisitorState state) {
     /*
      * All Guava guard methods accept a value to be checked, a format string and zero or more
@@ -271,7 +271,7 @@ public final class RedundantStringConversion extends BugChecker
   // number of arguments of the appropriate type. Also flag explicit conversions from `Throwable` to
   // string as the last logger argument. Suggests either dropping the conversion or going with
   // `Throwable#getMessage()` instead.
-  private Optional<SuggestedFix.Builder> tryFixSlf4jLogger(
+  private SuggestedFix tryFixSlf4jLogger(
       List<? extends ExpressionTree> arguments, VisitorState state) {
     /*
      * SLF4J treats the final argument to a log statement specially if it is a `Throwable`: it
@@ -291,36 +291,34 @@ public final class RedundantStringConversion extends BugChecker
         omitLast ? arguments.subList(0, arguments.size() - 1) : arguments, state, MARKER, ANY_EXPR);
   }
 
-  private Optional<SuggestedFix.Builder> tryFixFormatterArguments(
+  private SuggestedFix tryFixFormatterArguments(
       List<? extends ExpressionTree> arguments,
       VisitorState state,
       Matcher<ExpressionTree> firstArgFilter,
       Matcher<ExpressionTree> remainingArgFilter) {
     if (arguments.isEmpty()) {
       /* This format method accepts no arguments. Some odd overload? */
-      return Optional.empty();
+      return SuggestedFix.emptyFix();
     }
 
     int patternIndex = firstArgFilter.matches(arguments.get(0), state) ? 1 : 0;
     if (arguments.size() <= patternIndex) {
       /* This format method accepts only an ignored parameter. Some odd overload? */
-      return Optional.empty();
+      return SuggestedFix.emptyFix();
     }
 
     /* Simplify the values to be plugged into the format pattern, if possible. */
     return arguments.stream()
         .skip(patternIndex + 1L)
         .map(arg -> tryFix(arg, state, remainingArgFilter))
-        .flatMap(Optional::stream)
-        .reduce(SuggestedFix.Builder::merge);
+        .collect(SuggestedFix.mergeFixes());
   }
 
-  private Optional<SuggestedFix.Builder> tryFix(
+  private SuggestedFix tryFix(
       ExpressionTree tree, VisitorState state, Matcher<ExpressionTree> filter) {
     return trySimplify(tree, state, filter)
-        .map(
-            replacement ->
-                SuggestedFix.builder().replace(tree, SourceCode.treeToString(replacement, state)));
+        .map(replacement -> SuggestedFix.replace(tree, SourceCode.treeToString(replacement, state)))
+        .orElseGet(SuggestedFix::emptyFix);
   }
 
   private Optional<ExpressionTree> trySimplify(
@@ -369,20 +367,17 @@ public final class RedundantStringConversion extends BugChecker
     return Optional.of(Iterables.getOnlyElement(methodInvocation.getArguments()));
   }
 
-  private Description createDescription(Tree tree, Optional<SuggestedFix.Builder> fixes) {
-    return fixes
-        .map(SuggestedFix.Builder::build)
-        .map(fix -> describeMatch(tree, fix))
-        .orElse(Description.NO_MATCH);
+  private Description createDescription(Tree tree, SuggestedFix fix) {
+    return fix.isEmpty() ? Description.NO_MATCH : describeMatch(tree, fix);
   }
 
   private static Matcher<MethodInvocationTree> createConversionMethodMatcher(
       ErrorProneFlags flags) {
-    // XXX: ErrorProneFlags#getList splits by comma, but method signatures may also contain commas.
-    // For this class methods accepting more than one argument are not valid, but still: not nice.
+    // XXX: `Flags#getSet` splits by comma, but method signatures may also contain commas. For this
+    // class methods accepting more than one argument are not valid, but still: not nice.
     return anyOf(
         WELL_KNOWN_STRING_CONVERSION_METHODS,
         new MethodMatcherFactory()
-            .create(Flags.getList(flags, EXTRA_STRING_CONVERSION_METHODS_FLAG)));
+            .create(Flags.getSet(flags, EXTRA_STRING_CONVERSION_METHODS_FLAG)));
   }
 }

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

@@ -0,0 +1,95 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.CUSTOM;
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
+
+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.LiteralTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.util.ASTHelpers;
+import com.sun.source.tree.LiteralTree;
+import tech.picnic.errorprone.utils.SourceCode;
+
+/** A {@link BugChecker} that flags string constants with extraneous escaping. */
+// XXX: Also cover `\"` sequences inside text blocks. Note that this requires a more subtle
+// approach, as double-quote characters will need to remain escaped if removing the backslash would
+// create a new sequence of three or more double-quotes. (TBD whether we'd like to enforce a
+// "preferred" approach to escaping, e.g. by always escaping the last of a triplet, such that the
+// over-all number of escaped characters is minimized.)
+// XXX: Also flag `'\"'` char literals.
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "Inside string expressions single quotes do not need to be escaped",
+    link = BUG_PATTERNS_BASE_URL + "RedundantStringEscape",
+    linkType = CUSTOM,
+    severity = SUGGESTION,
+    tags = SIMPLIFICATION)
+public final class RedundantStringEscape extends BugChecker implements LiteralTreeMatcher {
+  private static final long serialVersionUID = 1L;
+
+  /** Instantiates a new {@link RedundantStringEscape} instance. */
+  public RedundantStringEscape() {}
+
+  @Override
+  public Description matchLiteral(LiteralTree tree, VisitorState state) {
+    String constant = ASTHelpers.constValue(tree, String.class);
+    if (constant == null || constant.indexOf('\'') < 0) {
+      /* Fast path: this isn't a string constant with a single quote. */
+      return Description.NO_MATCH;
+    }
+
+    String source = SourceCode.treeToString(tree, state);
+    if (!containsBannedEscapeSequence(source)) {
+      /* Semi-fast path: this expression doesn't contain an escaped single quote. */
+      return Description.NO_MATCH;
+    }
+
+    /* Slow path: suggest dropping the escape characters. */
+    return describeMatch(tree, SuggestedFix.replace(tree, dropRedundantEscapeSequences(source)));
+  }
+
+  /**
+   * Tells whether the given string constant source expression contains an escaped single quote.
+   *
+   * @implNote As the input is a literal Java string expression, it will start and end with a double
+   *     quote; as such any found backslash will not be the string's final character.
+   */
+  private static boolean containsBannedEscapeSequence(String source) {
+    for (int p = source.indexOf('\\'); p != -1; p = source.indexOf('\\', p + 2)) {
+      if (source.charAt(p + 1) == '\'') {
+        return true;
+      }
+    }
+
+    return false;
+  }
+
+  /**
+   * Simplifies the given string constant source expression by dropping the backslash preceding an
+   * escaped single quote.
+   *
+   * @implNote Note that this method does not delegate to {@link
+   *     SourceCode#toStringConstantExpression}, as that operation may replace other Unicode
+   *     characters with their associated escape sequence.
+   * @implNote As the input is a literal Java string expression, it will start and end with a double
+   *     quote; as such any found backslash will not be the string's final character.
+   */
+  private static String dropRedundantEscapeSequences(String source) {
+    StringBuilder result = new StringBuilder();
+
+    for (int p = 0; p < source.length(); p++) {
+      char c = source.charAt(p);
+      if (c != '\\' || source.charAt(p + 1) != '\'') {
+        result.append(c);
+      }
+    }
+
+    return result.toString();
+  }
+}

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

@@ -15,8 +15,8 @@ import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
 import com.google.common.collect.ImmutableCollection;
-import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableSet;
 import com.google.errorprone.BugPattern;
 import com.google.errorprone.ErrorProneFlags;
 import com.google.errorprone.VisitorState;
@@ -74,10 +74,10 @@ public final class RequestParamType extends BugChecker implements VariableTreeMa
     return allOf(
         annotations(AT_LEAST_ONE, isType("org.springframework.web.bind.annotation.RequestParam")),
         anyOf(isSubtypeOf(ImmutableCollection.class), isSubtypeOf(ImmutableMap.class)),
-        not(isSubtypeOfAny(Flags.getList(flags, SUPPORTED_CUSTOM_TYPES_FLAG))));
+        not(isSubtypeOfAny(Flags.getSet(flags, SUPPORTED_CUSTOM_TYPES_FLAG))));
   }
 
-  private static Matcher<Tree> isSubtypeOfAny(ImmutableList<String> inclusions) {
+  private static Matcher<Tree> isSubtypeOfAny(ImmutableSet<String> inclusions) {
     return anyOf(
         inclusions.stream()
             .map(inclusion -> isSubtypeOf(Suppliers.typeFromString(inclusion)))

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

@@ -41,7 +41,7 @@ import tech.picnic.errorprone.utils.SourceCode;
     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> SLF4J_MARKER = isSubtypeOf("org.slf4j.Marker");
   private static final Matcher<ExpressionTree> THROWABLE = isSubtypeOf(Throwable.class);
   private static final Matcher<ExpressionTree> SLF4J_LOGGER_INVOCATION =
       instanceMethod()
@@ -71,7 +71,7 @@ public final class Slf4jLogStatement extends BugChecker implements MethodInvocat
      * SLF4J log statements may accept a "marker" as a first argument, before the format string.
      * We ignore such markers.
      */
-    int lTrim = MARKER.matches(args.get(0), state) ? 1 : 0;
+    int lTrim = SLF4J_MARKER.matches(args.get(0), state) ? 1 : 0;
     /*
      * SLF4J treats the final argument to a log statement specially if it is a `Throwabe`: it
      * will always choose to render the associated stacktrace, even if the argument has a

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/Slf4jLoggerDeclaration.java

@@ -0,0 +1,185 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.common.base.Verify.verify;
+import static com.google.errorprone.BugPattern.LinkType.CUSTOM;
+import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
+import static com.google.errorprone.BugPattern.StandardTags.STYLE;
+import static com.google.errorprone.matchers.Matchers.allOf;
+import static com.google.errorprone.matchers.Matchers.classLiteral;
+import static com.google.errorprone.matchers.Matchers.instanceMethod;
+import static com.google.errorprone.matchers.Matchers.staticMethod;
+import static com.google.errorprone.matchers.Matchers.toType;
+import static java.util.Objects.requireNonNull;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
+
+import com.google.auto.service.AutoService;
+import com.google.common.base.CaseFormat;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Iterables;
+import com.google.common.collect.Sets;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.ErrorProneFlags;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.VariableTreeMatcher;
+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.sun.source.tree.ClassTree;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.MethodInvocationTree;
+import com.sun.source.tree.ModifiersTree;
+import com.sun.source.tree.Tree.Kind;
+import com.sun.source.tree.VariableTree;
+import com.sun.tools.javac.code.Symbol;
+import java.util.EnumSet;
+import javax.inject.Inject;
+import javax.lang.model.element.Modifier;
+import tech.picnic.errorprone.utils.MoreASTHelpers;
+
+/** A {@link BugChecker} that flags non-canonical SLF4J logger declarations. */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "SLF4J logger declarations should follow established best-practices",
+    link = BUG_PATTERNS_BASE_URL + "Slf4jLoggerDeclaration",
+    linkType = CUSTOM,
+    severity = WARNING,
+    tags = STYLE)
+@SuppressWarnings("java:S2160" /* Super class equality definition suffices. */)
+public final class Slf4jLoggerDeclaration extends BugChecker implements VariableTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Matcher<ExpressionTree> IS_GET_LOGGER =
+      staticMethod().onDescendantOf("org.slf4j.LoggerFactory").named("getLogger");
+  private static final String CANONICAL_STATIC_LOGGER_NAME_FLAG =
+      "Slf4jLoggerDeclaration:CanonicalStaticLoggerName";
+  private static final String DEFAULT_CANONICAL_LOGGER_NAME = "LOG";
+  private static final Matcher<ExpressionTree> IS_STATIC_ENCLOSING_CLASS_REFERENCE =
+      classLiteral(Slf4jLoggerDeclaration::isEnclosingClassReference);
+  private static final Matcher<ExpressionTree> IS_DYNAMIC_ENCLOSING_CLASS_REFERENCE =
+      toType(
+          MethodInvocationTree.class,
+          allOf(
+              instanceMethod().anyClass().named("getClass").withNoParameters(),
+              Slf4jLoggerDeclaration::getClassReceiverIsEnclosingClassInstance));
+  private static final ImmutableSet<Modifier> INSTANCE_DECLARATION_MODIFIERS =
+      Sets.immutableEnumSet(Modifier.PRIVATE, Modifier.FINAL);
+  private static final ImmutableSet<Modifier> STATIC_DECLARATION_MODIFIERS =
+      Sets.immutableEnumSet(Modifier.PRIVATE, Modifier.STATIC, Modifier.FINAL);
+
+  private final String canonicalStaticFieldName;
+  private final String canonicalInstanceFieldName;
+
+  /** Instantiates a default {@link Slf4jLoggerDeclaration} instance. */
+  public Slf4jLoggerDeclaration() {
+    this(ErrorProneFlags.empty());
+  }
+
+  /**
+   * Instantiates a customized {@link Slf4jLoggerDeclaration}.
+   *
+   * @param flags Any provided command line flags.
+   */
+  @Inject
+  Slf4jLoggerDeclaration(ErrorProneFlags flags) {
+    canonicalStaticFieldName =
+        flags.get(CANONICAL_STATIC_LOGGER_NAME_FLAG).orElse(DEFAULT_CANONICAL_LOGGER_NAME);
+    canonicalInstanceFieldName =
+        CaseFormat.UPPER_UNDERSCORE.to(CaseFormat.LOWER_CAMEL, canonicalStaticFieldName);
+  }
+
+  @Override
+  public Description matchVariable(VariableTree tree, VisitorState state) {
+    ExpressionTree initializer = tree.getInitializer();
+    if (!IS_GET_LOGGER.matches(initializer, state)) {
+      return Description.NO_MATCH;
+    }
+
+    ClassTree clazz = getEnclosingClass(state);
+    ExpressionTree factoryArg =
+        Iterables.getOnlyElement(((MethodInvocationTree) initializer).getArguments());
+
+    SuggestedFix.Builder fix = SuggestedFix.builder();
+
+    if (clazz.getModifiers().getFlags().contains(Modifier.ABSTRACT)
+        && IS_DYNAMIC_ENCLOSING_CLASS_REFERENCE.matches(factoryArg, state)) {
+      /*
+       * While generally we prefer `Logger` declarations to be static and named after their
+       * enclosing class, we allow one exception: loggers in abstract classes with a name derived
+       * from `getClass()`.
+       */
+      suggestModifiers(tree, INSTANCE_DECLARATION_MODIFIERS, fix, state);
+      suggestRename(tree, canonicalInstanceFieldName, fix, state);
+    } else {
+      suggestModifiers(
+          tree,
+          clazz.getKind() == Kind.INTERFACE ? ImmutableSet.of() : STATIC_DECLARATION_MODIFIERS,
+          fix,
+          state);
+      suggestRename(tree, canonicalStaticFieldName, fix, state);
+
+      if (!MoreASTHelpers.isStringTyped(factoryArg, state)
+          && !IS_STATIC_ENCLOSING_CLASS_REFERENCE.matches(factoryArg, state)) {
+        /*
+         * Loggers with a custom string name are generally "special", but those with a name derived
+         * from a class other than the one that encloses it are likely in error.
+         */
+        fix.merge(SuggestedFix.replace(factoryArg, clazz.getSimpleName() + ".class"));
+      }
+    }
+
+    return fix.isEmpty() ? Description.NO_MATCH : describeMatch(tree, fix.build());
+  }
+
+  private static void suggestModifiers(
+      VariableTree tree,
+      ImmutableSet<Modifier> modifiers,
+      SuggestedFix.Builder fixBuilder,
+      VisitorState state) {
+    ModifiersTree modifiersTree =
+        requireNonNull(ASTHelpers.getModifiers(tree), "`VariableTree` must have modifiers");
+    SuggestedFixes.addModifiers(tree, modifiersTree, state, modifiers).ifPresent(fixBuilder::merge);
+    SuggestedFixes.removeModifiers(
+            modifiersTree, state, Sets.difference(EnumSet.allOf(Modifier.class), modifiers))
+        .ifPresent(fixBuilder::merge);
+  }
+
+  private static void suggestRename(
+      VariableTree variableTree, String name, SuggestedFix.Builder fixBuilder, VisitorState state) {
+    if (!variableTree.getName().contentEquals(name)) {
+      fixBuilder.merge(SuggestedFixes.renameVariable(variableTree, name, state));
+    }
+  }
+
+  private static boolean isEnclosingClassReference(ExpressionTree tree, VisitorState state) {
+    return ASTHelpers.getSymbol(getEnclosingClass(state)).equals(ASTHelpers.getSymbol(tree));
+  }
+
+  private static boolean getClassReceiverIsEnclosingClassInstance(
+      MethodInvocationTree getClassInvocationTree, VisitorState state) {
+    ExpressionTree receiver = ASTHelpers.getReceiver(getClassInvocationTree);
+    if (receiver == null) {
+      /*
+       * Method invocations without an explicit receiver either involve static methods (possibly
+       * statically imported), or instance methods invoked on the enclosing class. As the given
+       * `getClassInvocationTree` is guaranteed to be a nullary `#getClass()` invocation, the latter
+       * must be the case.
+       */
+      return true;
+    }
+
+    Symbol symbol = ASTHelpers.getSymbol(receiver);
+    return symbol != null
+        && symbol.asType().tsym.equals(ASTHelpers.getSymbol(getEnclosingClass(state)));
+  }
+
+  private static ClassTree getEnclosingClass(VisitorState state) {
+    ClassTree clazz = state.findEnclosing(ClassTree.class);
+    // XXX: Review whether we should relax this constraint in the face of so-called anonymous
+    // classes. See
+    // https://docs.oracle.com/en/java/javase/23/language/implicitly-declared-classes-and-instance-main-methods.html
+    verify(clazz != null, "Variable not defined inside class");
+    return clazz;
+  }
+}

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

@@ -15,7 +15,6 @@ 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.Fix;
 import com.google.errorprone.fixes.SuggestedFix;
 import com.google.errorprone.fixes.SuggestedFixes;
 import com.google.errorprone.matchers.Description;
@@ -65,16 +64,18 @@ public final class SpringMvcAnnotation extends BugChecker implements AnnotationT
     return ARGUMENT_SELECTOR
         .extractMatchingArguments(tree)
         .findFirst()
-        .flatMap(arg -> trySimplification(tree, arg, state))
+        .map(arg -> trySimplification(tree, arg, state))
+        .filter(not(SuggestedFix::isEmpty))
         .map(fix -> describeMatch(tree, fix))
         .orElse(Description.NO_MATCH);
   }
 
-  private static Optional<Fix> trySimplification(
+  private static SuggestedFix trySimplification(
       AnnotationTree tree, ExpressionTree arg, VisitorState state) {
     return extractUniqueMethod(arg, state)
         .map(REPLACEMENTS::get)
-        .map(newAnnotation -> replaceAnnotation(tree, arg, newAnnotation, state));
+        .map(newAnnotation -> replaceAnnotation(tree, arg, newAnnotation, state))
+        .orElseGet(SuggestedFix::emptyFix);
   }
 
   private static Optional<String> extractUniqueMethod(ExpressionTree arg, VisitorState state) {
@@ -99,7 +100,7 @@ public final class SpringMvcAnnotation extends BugChecker implements AnnotationT
     };
   }
 
-  private static Fix replaceAnnotation(
+  private static SuggestedFix replaceAnnotation(
       AnnotationTree tree, ExpressionTree argToRemove, String newAnnotation, VisitorState state) {
     String newArguments =
         tree.getArguments().stream()

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

@@ -4,6 +4,7 @@ import static com.google.errorprone.BugPattern.LinkType.CUSTOM;
 import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
 import static com.google.errorprone.BugPattern.StandardTags.STYLE;
 import static java.util.Objects.requireNonNull;
+import static java.util.function.Predicate.not;
 import static tech.picnic.errorprone.bugpatterns.NonStaticImport.NON_STATIC_IMPORT_CANDIDATE_IDENTIFIERS;
 import static tech.picnic.errorprone.bugpatterns.NonStaticImport.NON_STATIC_IMPORT_CANDIDATE_MEMBERS;
 import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
@@ -34,7 +35,6 @@ import com.google.errorprone.bugpatterns.BugChecker;
 import com.google.errorprone.bugpatterns.BugChecker.MemberSelectTreeMatcher;
 import com.google.errorprone.bugpatterns.StaticImports;
 import com.google.errorprone.bugpatterns.StaticImports.StaticImportInfo;
-import com.google.errorprone.fixes.Fix;
 import com.google.errorprone.fixes.SuggestedFix;
 import com.google.errorprone.fixes.SuggestedFixes;
 import com.google.errorprone.matchers.Description;
@@ -203,7 +203,8 @@ public final class StaticImport extends BugChecker implements MemberSelectTreeMa
     }
 
     return getCandidateSimpleName(importInfo)
-        .flatMap(n -> tryStaticImport(tree, importInfo.canonicalName() + '.' + n, n, state))
+        .map(n -> tryStaticImport(tree, importInfo.canonicalName() + '.' + n, n, state))
+        .filter(not(SuggestedFix::isEmpty))
         .map(fix -> describeMatch(tree, fix))
         .orElse(Description.NO_MATCH);
   }
@@ -240,15 +241,15 @@ public final class StaticImport extends BugChecker implements MemberSelectTreeMa
                     || STATIC_IMPORT_CANDIDATE_MEMBERS.containsEntry(canonicalName, name));
   }
 
-  private static Optional<Fix> tryStaticImport(
+  private static SuggestedFix tryStaticImport(
       MemberSelectTree tree, String fullyQualifiedName, String simpleName, VisitorState state) {
     SuggestedFix.Builder fix = SuggestedFix.builder().replace(tree, simpleName);
 
     if (!simpleName.equals(SuggestedFixes.qualifyStaticImport(fullyQualifiedName, fix, state))) {
       /* Statically importing this symbol would clash with an existing import. */
-      return Optional.empty();
+      return SuggestedFix.emptyFix();
     }
 
-    return Optional.of(fix.build());
+    return fix.build();
   }
 }

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

@@ -23,7 +23,6 @@ import com.google.errorprone.util.ASTHelpers;
 import com.sun.source.tree.ExpressionTree;
 import com.sun.source.tree.MethodInvocationTree;
 import com.sun.tools.javac.code.Type;
-import com.sun.tools.javac.util.Constants;
 import java.util.Formattable;
 import java.util.Iterator;
 import java.util.List;
@@ -150,7 +149,7 @@ public final class StringJoin extends BugChecker implements MethodInvocationTree
     SuggestedFix.Builder fix =
         SuggestedFix.builder()
             .replace(tree.getMethodSelect(), "String.join")
-            .replace(arguments.next(), Constants.format(separator));
+            .replace(arguments.next(), SourceCode.toStringConstantExpression(separator, state));
 
     while (arguments.hasNext()) {
       ExpressionTree argument = arguments.next();

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/AssortedRules.java

@@ -1,8 +1,6 @@
 package tech.picnic.errorprone.refasterrules;
 
 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;
@@ -70,28 +68,6 @@ final class AssortedRules {
     }
   }
 
-  /**
-   * Use {@link Sets#toImmutableEnumSet()} when possible, as it is more efficient than {@link
-   * ImmutableSet#toImmutableSet()} and produces a more compact object.
-   *
-   * <p><strong>Warning:</strong> this rewrite rule is not completely behavior preserving: while the
-   * original code produces a set that iterates over the elements in encounter order, the
-   * replacement code iterates over the elements in enum definition order.
-   */
-  // XXX: ^ Consider emitting a comment warning about this fact?
-  static final class StreamToImmutableEnumSet<T extends Enum<T>> {
-    @BeforeTemplate
-    ImmutableSet<T> before(Stream<T> stream) {
-      return stream.collect(toImmutableSet());
-    }
-
-    @AfterTemplate
-    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
-    ImmutableSet<T> after(Stream<T> stream) {
-      return stream.collect(toImmutableEnumSet());
-    }
-  }
-
   /** Prefer {@link Iterators#getNext(Iterator, Object)} over more contrived alternatives. */
   static final class IteratorGetNextOrDefault<T> {
     @BeforeTemplate

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/BugCheckerRules.java

@@ -9,7 +9,9 @@ import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import com.sun.tools.javac.util.Constants;
 import com.sun.tools.javac.util.Convert;
+import javax.lang.model.element.Name;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
+import tech.picnic.errorprone.utils.SourceCode;
 
 /** Refaster rules related to {@link com.google.errorprone.bugpatterns.BugChecker} classes. */
 @OnlineDocumentation
@@ -55,16 +57,44 @@ final class BugCheckerRules {
     }
   }
 
-  /** Prefer using the {@link Constants} API over more verbose alternatives. */
+  /**
+   * Prefer {@link SourceCode#toStringConstantExpression(Object,
+   * com.google.errorprone.VisitorState)} over alternatives that unnecessarily escape single quote
+   * characters.
+   */
   static final class ConstantsFormat {
+    @BeforeTemplate
+    String before(CharSequence value) {
+      return Constants.format(value);
+    }
+
     @BeforeTemplate
     String before(String value) {
       return String.format("\"%s\"", Convert.quote(value));
     }
 
     @AfterTemplate
-    String after(String value) {
-      return Constants.format(value);
+    String after(CharSequence value) {
+      return SourceCode.toStringConstantExpression(
+          value, Refaster.emitCommentBefore("REPLACEME", null));
+    }
+  }
+
+  /** Prefer {@link Name#contentEquals(CharSequence)} over more verbose alternatives. */
+  static final class NameContentEquals {
+    @BeforeTemplate
+    boolean before(Name name, CharSequence string) {
+      return name.toString().equals(string.toString());
+    }
+
+    @BeforeTemplate
+    boolean before(Name name, String string) {
+      return name.toString().equals(string);
+    }
+
+    @AfterTemplate
+    boolean after(Name name, CharSequence string) {
+      return name.contentEquals(string);
     }
   }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/ClassRules.java

@@ -3,6 +3,7 @@ package tech.picnic.errorprone.refasterrules;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import java.util.function.Function;
 import java.util.function.Predicate;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 
@@ -37,7 +38,12 @@ final class ClassRules {
     }
   }
 
-  /** Prefer {@link Class#isInstance(Object)} method references over more verbose alternatives. */
+  /**
+   * Prefer {@link Class#isInstance(Object)} method references over lambda expressions that require
+   * naming a variable.
+   */
+  // XXX: Once the `ClassReferenceIsInstancePredicate` rule is dropped, rename this rule to just
+  // `ClassIsInstancePredicate`.
   static final class ClassLiteralIsInstancePredicate<T, S> {
     @BeforeTemplate
     Predicate<S> before() {
@@ -50,7 +56,11 @@ final class ClassRules {
     }
   }
 
-  /** Prefer {@link Class#isInstance(Object)} method references over more verbose alternatives. */
+  /**
+   * Prefer {@link Class#isInstance(Object)} method references over lambda expressions that require
+   * naming a variable.
+   */
+  // XXX: Drop this rule once the `MethodReferenceUsage` rule is enabled by default.
   static final class ClassReferenceIsInstancePredicate<T, S> {
     @BeforeTemplate
     Predicate<S> before(Class<T> clazz) {
@@ -62,4 +72,21 @@ final class ClassRules {
       return clazz::isInstance;
     }
   }
+
+  /**
+   * Prefer {@link Class#cast(Object)} method references over lambda expressions that require naming
+   * a variable.
+   */
+  // XXX: Drop this rule once the `MethodReferenceUsage` rule is enabled by default.
+  static final class ClassReferenceCast<T, S> {
+    @BeforeTemplate
+    Function<T, S> before(Class<? extends S> clazz) {
+      return o -> clazz.cast(o);
+    }
+
+    @AfterTemplate
+    Function<T, S> after(Class<? extends S> clazz) {
+      return clazz::cast;
+    }
+  }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/CollectionRules.java

@@ -8,7 +8,9 @@ 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.NotMatches;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.List;
@@ -21,6 +23,7 @@ import java.util.function.Consumer;
 import java.util.function.IntFunction;
 import java.util.stream.Stream;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
+import tech.picnic.errorprone.refaster.matchers.IsRefasterAsVarargs;
 
 /** Refaster rules related to expressions dealing with (arbitrary) collections. */
 // XXX: There are other Guava `Iterables` methods that should not be called if the input is known to
@@ -184,6 +187,24 @@ final class CollectionRules {
     }
   }
 
+  /** Don't unnecessarily call {@link Stream#distinct()} on an already-unique stream of elements. */
+  // XXX: This rule assumes that the `Set` relies on `Object#equals`, rather than a custom
+  // equivalence relation.
+  // XXX: Expressions that drop or reorder elements from the stream, such as `.filter`, `.skip` and
+  // `sorted`, can similarly be simplified. Covering all cases is better done using an Error Prone
+  // check.
+  static final class SetStream<T> {
+    @BeforeTemplate
+    Stream<?> before(Set<T> set) {
+      return set.stream().distinct();
+    }
+
+    @AfterTemplate
+    Stream<?> after(Set<T> set) {
+      return set.stream();
+    }
+  }
+
   /** Prefer {@link ArrayList#ArrayList(Collection)} over the Guava alternative. */
   @SuppressWarnings(
       "NonApiType" /* Matching against `List` would unnecessarily constrain the rule. */)
@@ -276,6 +297,23 @@ final class CollectionRules {
     }
   }
 
+  /** Prefer {@link Arrays#asList(Object[])} over more contrived alternatives. */
+  // XXX: Consider moving this rule to `ImmutableListRules` and having it suggest
+  // `ImmutableList#copyOf`. That would retain immutability, at the cost of no longer handling
+  // `null`s.
+  static final class ArraysAsList<T> {
+    // XXX: This expression produces an unmodifiable list, while the alternative doesn't.
+    @BeforeTemplate
+    List<T> before(@NotMatches(IsRefasterAsVarargs.class) T[] array) {
+      return Arrays.stream(array).toList();
+    }
+
+    @AfterTemplate
+    List<T> after(T[] array) {
+      return Arrays.asList(array);
+    }
+  }
+
   /** Prefer calling {@link Collection#toArray()} over more contrived alternatives. */
   static final class CollectionToArray<T> {
     @BeforeTemplate
@@ -327,18 +365,20 @@ final class CollectionRules {
     }
   }
 
-  /**
-   * Don't call {@link ImmutableCollection#asList()} if {@link ImmutableCollection#iterator()} is
-   * called on the result; call it directly.
-   */
-  static final class ImmutableCollectionIterator<T> {
+  /** Prefer {@link Collection#iterator()} over more contrived or less efficient alternatives. */
+  static final class CollectionIterator<T> {
+    @BeforeTemplate
+    Iterator<T> before(Collection<T> collection) {
+      return collection.stream().iterator();
+    }
+
     @BeforeTemplate
     Iterator<T> before(ImmutableCollection<T> collection) {
       return collection.asList().iterator();
     }
 
     @AfterTemplate
-    Iterator<T> after(ImmutableCollection<T> collection) {
+    Iterator<T> after(Collection<T> collection) {
       return collection.iterator();
     }
   }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/ComparatorRules.java

@@ -24,8 +24,10 @@ import com.google.errorprone.refaster.annotation.Placeholder;
 import com.google.errorprone.refaster.annotation.Repeated;
 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.List;
 import java.util.Optional;
 import java.util.function.BinaryOperator;
 import java.util.function.Function;
@@ -243,18 +245,77 @@ final class ComparatorRules {
     }
   }
 
+  /** Prefer {@link Collections#sort(List)} over more verbose alternatives. */
+  static final class CollectionsSort<T extends Comparable<? super T>> {
+    @BeforeTemplate
+    void before(List<T> collection) {
+      Collections.sort(collection, naturalOrder());
+    }
+
+    @AfterTemplate
+    void after(List<T> collection) {
+      Collections.sort(collection);
+    }
+  }
+
+  /** Prefer {@link Collections#min(Collection)} over more verbose alternatives. */
+  static final class CollectionsMin<T extends Comparable<? super T>> {
+    @BeforeTemplate
+    T before(Collection<T> collection) {
+      return Refaster.anyOf(
+          Collections.min(collection, naturalOrder()), Collections.max(collection, reverseOrder()));
+    }
+
+    @AfterTemplate
+    T after(Collection<T> collection) {
+      return Collections.min(collection);
+    }
+  }
+
   /**
    * Avoid unnecessary creation of a {@link Stream} to determine the minimum of a known collection
    * of values.
    */
-  static final class MinOfVarargs<T> {
+  static final class MinOfArray<S, T extends S> {
     @BeforeTemplate
-    T before(@Repeated T value, Comparator<T> cmp) {
+    T before(T[] array, Comparator<S> cmp) {
+      return Arrays.stream(array).min(cmp).orElseThrow();
+    }
+
+    @AfterTemplate
+    T after(T[] array, Comparator<S> cmp) {
+      return Collections.min(Arrays.asList(array), cmp);
+    }
+  }
+
+  /**
+   * Avoid unnecessary creation of a {@link Stream} to determine the minimum of a known collection
+   * of values.
+   */
+  static final class CollectionsMinWithComparator<S, T extends S> {
+    @BeforeTemplate
+    T before(Collection<T> collection, Comparator<S> cmp) {
+      return collection.stream().min(cmp).orElseThrow();
+    }
+
+    @AfterTemplate
+    T after(Collection<T> collection, Comparator<S> cmp) {
+      return Collections.min(collection, cmp);
+    }
+  }
+
+  /**
+   * Avoid unnecessary creation of a {@link Stream} to determine the minimum of a known collection
+   * of values.
+   */
+  static final class MinOfVarargs<S, T extends S> {
+    @BeforeTemplate
+    T before(@Repeated T value, Comparator<S> cmp) {
       return Stream.of(Refaster.asVarargs(value)).min(cmp).orElseThrow();
     }
 
     @AfterTemplate
-    T after(@Repeated T value, Comparator<T> cmp) {
+    T after(@Repeated T value, Comparator<S> cmp) {
       return Collections.min(Arrays.asList(value), cmp);
     }
   }
@@ -310,18 +371,64 @@ final class ComparatorRules {
     }
   }
 
+  /** Prefer {@link Collections#max(Collection)} over more verbose alternatives. */
+  static final class CollectionsMax<T extends Comparable<? super T>> {
+    @BeforeTemplate
+    T before(Collection<T> collection) {
+      return Refaster.anyOf(
+          Collections.max(collection, naturalOrder()), Collections.min(collection, reverseOrder()));
+    }
+
+    @AfterTemplate
+    T after(Collection<T> collection) {
+      return Collections.max(collection);
+    }
+  }
+
   /**
    * Avoid unnecessary creation of a {@link Stream} to determine the maximum of a known collection
    * of values.
    */
-  static final class MaxOfVarargs<T> {
+  static final class MaxOfArray<S, T extends S> {
     @BeforeTemplate
-    T before(@Repeated T value, Comparator<T> cmp) {
+    T before(T[] array, Comparator<S> cmp) {
+      return Arrays.stream(array).max(cmp).orElseThrow();
+    }
+
+    @AfterTemplate
+    T after(T[] array, Comparator<S> cmp) {
+      return Collections.max(Arrays.asList(array), cmp);
+    }
+  }
+
+  /**
+   * Avoid unnecessary creation of a {@link Stream} to determine the maximum of a known collection
+   * of values.
+   */
+  static final class CollectionsMaxWithComparator<S, T extends S> {
+    @BeforeTemplate
+    T before(Collection<T> collection, Comparator<S> cmp) {
+      return collection.stream().max(cmp).orElseThrow();
+    }
+
+    @AfterTemplate
+    T after(Collection<T> collection, Comparator<S> cmp) {
+      return Collections.max(collection, cmp);
+    }
+  }
+
+  /**
+   * Avoid unnecessary creation of a {@link Stream} to determine the maximum of a known collection
+   * of values.
+   */
+  static final class MaxOfVarargs<S, T extends S> {
+    @BeforeTemplate
+    T before(@Repeated T value, Comparator<S> cmp) {
       return Stream.of(Refaster.asVarargs(value)).max(cmp).orElseThrow();
     }
 
     @AfterTemplate
-    T after(@Repeated T value, Comparator<T> cmp) {
+    T after(@Repeated T value, Comparator<S> cmp) {
       return Collections.max(Arrays.asList(value), cmp);
     }
   }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/FileRules.java

@@ -2,12 +2,18 @@ package tech.picnic.errorprone.refasterrules;
 
 import static java.nio.charset.StandardCharsets.UTF_8;
 
+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.io.File;
 import java.io.IOException;
+import java.net.URI;
 import java.nio.charset.Charset;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.attribute.FileAttribute;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 
 /** Refaster rules related to expressions dealing with files. */
@@ -15,6 +21,49 @@ import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 final class FileRules {
   private FileRules() {}
 
+  /** Prefer the more idiomatic {@link Path#of(URI)} over {@link Paths#get(URI)}. */
+  static final class PathOfUri {
+    @BeforeTemplate
+    Path before(URI uri) {
+      return Paths.get(uri);
+    }
+
+    @AfterTemplate
+    Path after(URI uri) {
+      return Path.of(uri);
+    }
+  }
+
+  /**
+   * Prefer the more idiomatic {@link Path#of(String, String...)} over {@link Paths#get(String,
+   * String...)}.
+   */
+  static final class PathOfString {
+    @BeforeTemplate
+    Path before(String first, @Repeated String more) {
+      return Paths.get(first, more);
+    }
+
+    @AfterTemplate
+    Path after(String first, @Repeated String more) {
+      return Path.of(first, more);
+    }
+  }
+
+  /** Avoid redundant conversions from {@link Path} to {@link File}. */
+  // XXX: Review whether a rule such as this one is better handled by the `IdentityConversion` rule.
+  static final class PathInstance {
+    @BeforeTemplate
+    Path before(Path path) {
+      return path.toFile().toPath();
+    }
+
+    @AfterTemplate
+    Path after(Path path) {
+      return path;
+    }
+  }
+
   /** Prefer {@link Files#readString(Path, Charset)} over more contrived alternatives. */
   static final class FilesReadStringWithCharset {
     @BeforeTemplate
@@ -40,4 +89,56 @@ final class FileRules {
       return Files.readString(path);
     }
   }
+
+  /**
+   * Prefer {@link Files#createTempFile(String, String, FileAttribute[])} over alternatives that
+   * create files with more liberal permissions.
+   *
+   * <p>Note that {@link File#createTempFile} treats the given prefix as a path, and ignores all but
+   * its file name. That is, the actual prefix used is derived from all characters following the
+   * final file separator (if any). This is not the case with {@link Files#createTempFile}, which
+   * will instead throw an {@link IllegalArgumentException} if the prefix contains any file
+   * separators.
+   */
+  static final class FilesCreateTempFileToFile {
+    @BeforeTemplate
+    @SuppressWarnings({
+      "FilesCreateTempFileInCustomDirectoryToFile" /* This is a more specific template. */,
+      "java:S5443" /* This violation will be rewritten. */,
+      "key-to-resolve-AnnotationUseStyle-and-TrailingComment-check-conflict"
+    })
+    File before(String prefix, String suffix) throws IOException {
+      return Refaster.anyOf(
+          File.createTempFile(prefix, suffix), File.createTempFile(prefix, suffix, null));
+    }
+
+    @AfterTemplate
+    @SuppressWarnings(
+        "java:S5443" /* On POSIX systems the file will only have user read-write permissions. */)
+    File after(String prefix, String suffix) throws IOException {
+      return Files.createTempFile(prefix, suffix).toFile();
+    }
+  }
+
+  /**
+   * Prefer {@link Files#createTempFile(Path, String, String, FileAttribute[])} over alternatives
+   * that create files with more liberal permissions.
+   *
+   * <p>Note that {@link File#createTempFile} treats the given prefix as a path, and ignores all but
+   * its file name. That is, the actual prefix used is derived from all characters following the
+   * final file separator (if any). This is not the case with {@link Files#createTempFile}, which
+   * will instead throw an {@link IllegalArgumentException} if the prefix contains any file
+   * separators.
+   */
+  static final class FilesCreateTempFileInCustomDirectoryToFile {
+    @BeforeTemplate
+    File before(File directory, String prefix, String suffix) throws IOException {
+      return File.createTempFile(prefix, suffix, directory);
+    }
+
+    @AfterTemplate
+    File after(File directory, String prefix, String suffix) throws IOException {
+      return Files.createTempFile(directory.toPath(), prefix, suffix).toFile();
+    }
+  }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/ImmutableEnumSetRules.java

@@ -0,0 +1,246 @@
+package tech.picnic.errorprone.refasterrules;
+
+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 com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Sets;
+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 com.google.errorprone.refaster.annotation.UseImportPolicy;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.EnumSet;
+import java.util.stream.Stream;
+import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
+
+/**
+ * Refaster rules related to expressions dealing with {@code
+ * com.google.common.collect.ImmutableEnumSet}s.
+ */
+// XXX: Some of the rules defined here impact iteration order. That's a rather subtle change. Should
+// we emit a comment warning about this fact? (This may produce a lot of noise. A bug checker could
+// in some cases determine whether iteration order is important.)
+// XXX: Consider replacing the `SetsImmutableEnumSet[N]` Refaster rules with a bug checker, such
+// that call to `ImmutableSet#of(Object, Object, Object, Object, Object, Object, Object[])` with
+// enum-typed values can also be rewritten.
+@OnlineDocumentation
+final class ImmutableEnumSetRules {
+  private ImmutableEnumSetRules() {}
+
+  /**
+   * Prefer {@link Sets#immutableEnumSet(Iterable)} for enum collections to take advantage of the
+   * internally used {@link EnumSet}.
+   *
+   * <p><strong>Warning:</strong> this rule is not completely behavior preserving: while the
+   * original code produces a set that iterates over its elements in the same order as the input
+   * {@link Iterable}, the replacement code iterates over the elements in enum definition order.
+   */
+  static final class SetsImmutableEnumSetIterable<T extends Enum<T>> {
+    @BeforeTemplate
+    ImmutableSet<T> before(Iterable<T> elements) {
+      return ImmutableSet.copyOf(elements);
+    }
+
+    @BeforeTemplate
+    ImmutableSet<T> before(Collection<T> elements) {
+      return ImmutableSet.copyOf(elements);
+    }
+
+    @AfterTemplate
+    ImmutableSet<T> after(Iterable<T> elements) {
+      return Sets.immutableEnumSet(elements);
+    }
+  }
+
+  /**
+   * Prefer {@link Sets#immutableEnumSet(Iterable)} for enum collections to take advantage of the
+   * internally used {@link EnumSet}.
+   *
+   * <p><strong>Warning:</strong> this rule is not completely behavior preserving: while the
+   * original code produces a set that iterates over its elements in the same order as defined in
+   * the array, the replacement code iterates over the elements in enum definition order.
+   */
+  static final class SetsImmutableEnumSetArraysAsList<T extends Enum<T>> {
+    @BeforeTemplate
+    ImmutableSet<T> before(T[] elements) {
+      return ImmutableSet.copyOf(elements);
+    }
+
+    @AfterTemplate
+    ImmutableSet<T> after(T[] elements) {
+      return Sets.immutableEnumSet(Arrays.asList(elements));
+    }
+  }
+
+  /**
+   * Prefer {@link Sets#immutableEnumSet(Enum, Enum[])} for enum collections to take advantage of
+   * the internally used {@link EnumSet}.
+   */
+  static final class SetsImmutableEnumSet1<T extends Enum<T>> {
+    @BeforeTemplate
+    @SuppressWarnings("SetsImmutableEnumSetIterable" /* This is a more specific template. */)
+    ImmutableSet<T> before(T e1) {
+      return Refaster.anyOf(ImmutableSet.of(e1), ImmutableSet.copyOf(EnumSet.of(e1)));
+    }
+
+    @AfterTemplate
+    @SuppressWarnings("unchecked")
+    ImmutableSet<T> after(T e1) {
+      return Sets.immutableEnumSet(e1);
+    }
+  }
+
+  /**
+   * Prefer {@link Sets#immutableEnumSet(Enum, Enum[])} for enum collections to take advantage of
+   * the internally used {@link EnumSet}.
+   *
+   * <p><strong>Warning:</strong> this rule is not completely behavior preserving: while the {@link
+   * ImmutableSet#of} expression produces a set that iterates over its elements in the listed order,
+   * the replacement code iterates over the elements in enum definition order.
+   */
+  static final class SetsImmutableEnumSet2<T extends Enum<T>> {
+    @BeforeTemplate
+    @SuppressWarnings("SetsImmutableEnumSetIterable" /* This is a more specific template. */)
+    ImmutableSet<T> before(T e1, T e2) {
+      return Refaster.anyOf(ImmutableSet.of(e1, e2), ImmutableSet.copyOf(EnumSet.of(e1, e2)));
+    }
+
+    @AfterTemplate
+    @SuppressWarnings("unchecked")
+    ImmutableSet<T> after(T e1, T e2) {
+      return Sets.immutableEnumSet(e1, e2);
+    }
+  }
+
+  /**
+   * Prefer {@link Sets#immutableEnumSet(Enum, Enum[])} for enum collections to take advantage of
+   * the internally used {@link EnumSet}.
+   *
+   * <p><strong>Warning:</strong> this rule is not completely behavior preserving: while the {@link
+   * ImmutableSet#of} expression produces a set that iterates over its elements in the listed order,
+   * the replacement code iterates over the elements in enum definition order.
+   */
+  static final class SetsImmutableEnumSet3<T extends Enum<T>> {
+    @BeforeTemplate
+    @SuppressWarnings("SetsImmutableEnumSetIterable" /* This is a more specific template. */)
+    ImmutableSet<T> before(T e1, T e2, T e3) {
+      return Refaster.anyOf(
+          ImmutableSet.of(e1, e2, e3), ImmutableSet.copyOf(EnumSet.of(e1, e2, e3)));
+    }
+
+    @AfterTemplate
+    @SuppressWarnings("unchecked")
+    ImmutableSet<T> after(T e1, T e2, T e3) {
+      return Sets.immutableEnumSet(e1, e2, e3);
+    }
+  }
+
+  /**
+   * Prefer {@link Sets#immutableEnumSet(Enum, Enum[])} for enum collections to take advantage of
+   * the internally used {@link EnumSet}.
+   *
+   * <p><strong>Warning:</strong> this rule is not completely behavior preserving: while the {@link
+   * ImmutableSet#of} expression produces a set that iterates over its elements in the listed order,
+   * the replacement code iterates over the elements in enum definition order.
+   */
+  static final class SetsImmutableEnumSet4<T extends Enum<T>> {
+    @BeforeTemplate
+    @SuppressWarnings("SetsImmutableEnumSetIterable" /* This is a more specific template. */)
+    ImmutableSet<T> before(T e1, T e2, T e3, T e4) {
+      return Refaster.anyOf(
+          ImmutableSet.of(e1, e2, e3, e4), ImmutableSet.copyOf(EnumSet.of(e1, e2, e3, e4)));
+    }
+
+    @AfterTemplate
+    @SuppressWarnings("unchecked")
+    ImmutableSet<T> after(T e1, T e2, T e3, T e4) {
+      return Sets.immutableEnumSet(e1, e2, e3, e4);
+    }
+  }
+
+  /**
+   * Prefer {@link Sets#immutableEnumSet(Enum, Enum[])} for enum collections to take advantage of
+   * the internally used {@link EnumSet}.
+   *
+   * <p><strong>Warning:</strong> this rule is not completely behavior preserving: while the {@link
+   * ImmutableSet#of} expression produces a set that iterates over its elements in the listed order,
+   * the replacement code iterates over the elements in enum definition order.
+   */
+  static final class SetsImmutableEnumSet5<T extends Enum<T>> {
+    @BeforeTemplate
+    @SuppressWarnings("SetsImmutableEnumSetIterable" /* This is a more specific template. */)
+    ImmutableSet<T> before(T e1, T e2, T e3, T e4, T e5) {
+      return Refaster.anyOf(
+          ImmutableSet.of(e1, e2, e3, e4, e5), ImmutableSet.copyOf(EnumSet.of(e1, e2, e3, e4, e5)));
+    }
+
+    @AfterTemplate
+    @SuppressWarnings("unchecked")
+    ImmutableSet<T> after(T e1, T e2, T e3, T e4, T e5) {
+      return Sets.immutableEnumSet(e1, e2, e3, e4, e5);
+    }
+  }
+
+  /**
+   * Prefer {@link Sets#immutableEnumSet(Enum, Enum[])} for enum collections to take advantage of
+   * the internally used {@link EnumSet}.
+   *
+   * <p><strong>Warning:</strong> this rule is not completely behavior preserving: while the
+   * original code produces a set that iterates over its elements in the listed order, the
+   * replacement code iterates over the elements in enum definition order.
+   */
+  static final class SetsImmutableEnumSet6<T extends Enum<T>> {
+    @BeforeTemplate
+    ImmutableSet<T> before(T e1, T e2, T e3, T e4, T e5, T e6) {
+      return ImmutableSet.of(e1, e2, e3, e4, e5, e6);
+    }
+
+    @AfterTemplate
+    @SuppressWarnings("unchecked")
+    ImmutableSet<T> after(T e1, T e2, T e3, T e4, T e5, T e6) {
+      return Sets.immutableEnumSet(e1, e2, e3, e4, e5, e6);
+    }
+  }
+
+  /**
+   * Prefer {@link Sets#immutableEnumSet(Enum, Enum[])} for enum collections to take advantage of
+   * the internally used {@link EnumSet}.
+   */
+  static final class SetsImmutableEnumSetVarArgs<T extends Enum<T>> {
+    @BeforeTemplate
+    @SuppressWarnings("SetsImmutableEnumSetIterable" /* This is a more specific template. */)
+    ImmutableSet<T> before(T e1, @Repeated T elements) {
+      return ImmutableSet.copyOf(EnumSet.of(e1, Refaster.asVarargs(elements)));
+    }
+
+    @AfterTemplate
+    ImmutableSet<T> after(T e1, @Repeated T elements) {
+      return Sets.immutableEnumSet(e1, Refaster.asVarargs(elements));
+    }
+  }
+
+  /**
+   * Use {@link Sets#toImmutableEnumSet()} when possible, as it is more efficient than {@link
+   * ImmutableSet#toImmutableSet()} and produces a more compact object.
+   *
+   * <p><strong>Warning:</strong> this rule is not completely behavior preserving: while the
+   * original code produces a set that iterates over its elements in encounter order, the
+   * replacement code iterates over the elements in enum definition order.
+   */
+  static final class StreamToImmutableEnumSet<T extends Enum<T>> {
+    @BeforeTemplate
+    ImmutableSet<T> before(Stream<T> stream) {
+      return stream.collect(toImmutableSet());
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    ImmutableSet<T> after(Stream<T> stream) {
+      return stream.collect(toImmutableEnumSet());
+    }
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/MicrometerRules.java

@@ -0,0 +1,88 @@
+package tech.picnic.errorprone.refasterrules;
+
+import com.google.common.collect.ImmutableCollection;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import com.google.errorprone.refaster.Refaster;
+import com.google.errorprone.refaster.annotation.AfterTemplate;
+import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import io.micrometer.core.instrument.Tag;
+import io.micrometer.core.instrument.Tags;
+import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
+
+/** Refaster rules related to expressions dealing with Micrometer. */
+// XXX: Consider replacing the `TagsOf[N]` rules with a bug checker, so that various other
+// expressions (e.g. those creating other collection types, those passing in tags some other way, or
+// those passing in more tags) can be replaced as wel.
+@OnlineDocumentation
+final class MicrometerRules {
+  private MicrometerRules() {}
+
+  /** Prefer using {@link Tags} over other immutable collections. */
+  static final class TagsOf1 {
+    @BeforeTemplate
+    ImmutableCollection<Tag> before(Tag tag) {
+      return Refaster.anyOf(ImmutableSet.of(tag), ImmutableList.of(tag));
+    }
+
+    @AfterTemplate
+    Iterable<Tag> after(Tag tag) {
+      return Tags.of(tag);
+    }
+  }
+
+  /** Prefer using {@link Tags} over other immutable collections. */
+  static final class TagsOf2 {
+    @BeforeTemplate
+    ImmutableCollection<Tag> before(Tag tag1, Tag tag2) {
+      return Refaster.anyOf(ImmutableSet.of(tag1, tag2), ImmutableList.of(tag1, tag2));
+    }
+
+    @AfterTemplate
+    Iterable<Tag> after(Tag tag1, Tag tag2) {
+      return Tags.of(tag1, tag2);
+    }
+  }
+
+  /** Prefer using {@link Tags} over other immutable collections. */
+  static final class TagsOf3 {
+    @BeforeTemplate
+    ImmutableCollection<Tag> before(Tag tag1, Tag tag2, Tag tag3) {
+      return Refaster.anyOf(ImmutableSet.of(tag1, tag2, tag3), ImmutableList.of(tag1, tag2, tag3));
+    }
+
+    @AfterTemplate
+    Iterable<Tag> after(Tag tag1, Tag tag2, Tag tag3) {
+      return Tags.of(tag1, tag2, tag3);
+    }
+  }
+
+  /** Prefer using {@link Tags} over other immutable collections. */
+  static final class TagsOf4 {
+    @BeforeTemplate
+    ImmutableCollection<Tag> before(Tag tag1, Tag tag2, Tag tag3, Tag tag4) {
+      return Refaster.anyOf(
+          ImmutableSet.of(tag1, tag2, tag3, tag4), ImmutableList.of(tag1, tag2, tag3, tag4));
+    }
+
+    @AfterTemplate
+    Iterable<Tag> after(Tag tag1, Tag tag2, Tag tag3, Tag tag4) {
+      return Tags.of(tag1, tag2, tag3, tag4);
+    }
+  }
+
+  /** Prefer using {@link Tags} over other immutable collections. */
+  static final class TagsOf5 {
+    @BeforeTemplate
+    ImmutableCollection<Tag> before(Tag tag1, Tag tag2, Tag tag3, Tag tag4, Tag tag5) {
+      return Refaster.anyOf(
+          ImmutableSet.of(tag1, tag2, tag3, tag4, tag5),
+          ImmutableList.of(tag1, tag2, tag3, tag4, tag5));
+    }
+
+    @AfterTemplate
+    Iterable<Tag> after(Tag tag1, Tag tag2, Tag tag3, Tag tag4, Tag tag5) {
+      return Tags.of(tag1, tag2, tag3, tag4, tag5);
+    }
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/OptionalRules.java

@@ -20,7 +20,7 @@ import java.util.function.Supplier;
 import java.util.stream.Stream;
 import org.jspecify.annotations.Nullable;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
-import tech.picnic.errorprone.refaster.matchers.IsLikelyTrivialComputation;
+import tech.picnic.errorprone.refaster.matchers.RequiresComputation;
 
 /** Refaster rules related to expressions dealing with {@link Optional}s. */
 @OnlineDocumentation
@@ -255,24 +255,21 @@ final class OptionalRules {
   }
 
   /**
-   * Prefer {@link Optional#orElseGet(Supplier)} over {@link Optional#orElse(Object)} if the
-   * fallback value is not the result of a trivial computation.
+   * Prefer {@link Optional#orElse(Object)} over {@link Optional#orElseGet(Supplier)} if the
+   * fallback value does not require non-trivial computation.
    */
-  // XXX: This rule may introduce a compilation error: the `value` expression may reference a
-  // non-effectively final variable, which is not allowed in the replacement lambda expression.
-  // Review whether a `@Matcher` can be used to avoid this.
-  // XXX: Once `MethodReferenceUsage` is "production ready", replace
-  // `@NotMatches(IsLikelyTrivialComputation.class)` with `@Matches(RequiresComputation.class)` (and
-  // reimplement the matcher accordingly).
-  static final class OptionalOrElseGet<T> {
+  // XXX: This rule is the counterpart to the `OptionalOrElseGet` bug checker. Once the
+  // `MethodReferenceUsage` bug checker is "production ready", that bug checker may similarly be
+  // replaced with a Refaster rule.
+  static final class OptionalOrElse<T> {
     @BeforeTemplate
-    T before(Optional<T> optional, @NotMatches(IsLikelyTrivialComputation.class) T value) {
-      return optional.orElse(value);
+    T before(Optional<T> optional, @NotMatches(RequiresComputation.class) T value) {
+      return optional.orElseGet(() -> value);
     }
 
     @AfterTemplate
     T after(Optional<T> optional, T value) {
-      return optional.orElseGet(() -> value);
+      return optional.orElse(value);
     }
   }
 
@@ -282,6 +279,9 @@ final class OptionalRules {
    */
   // XXX: Do we need the `.filter(Optional::isPresent)`? If it's absent the caller probably assumed
   // that the values are present. (If we drop it, we should rewrite vacuous filter steps.)
+  // XXX: The rewritten `filter`/`map` expression may be more performant than its replacement. See
+  // https://github.com/palantir/gradle-baseline/pull/2946. (There are plans to pair Refaster rules
+  // with JMH benchmarks; this would be a great use case.)
   static final class StreamFlatMapOptional<T> {
     @BeforeTemplate
     Stream<T> before(Stream<Optional<T>> stream) {
@@ -373,7 +373,12 @@ final class OptionalRules {
   /** Prefer {@link Optional#or(Supplier)} over more verbose alternatives. */
   static final class OptionalOrOtherOptional<T> {
     @BeforeTemplate
-    @SuppressWarnings("NestedOptionals")
+    @SuppressWarnings({
+      "LexicographicalAnnotationAttributeListing" /* `key-*` entry must remain last. */,
+      "NestedOptionals" /* This violation will be rewritten. */,
+      "OptionalOrElse" /* Parameters represent expressions that may require computation. */,
+      "key-to-resolve-AnnotationUseStyle-and-TrailingComment-check-conflict"
+    })
     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.
@@ -393,10 +398,7 @@ final class OptionalRules {
     }
   }
 
-  /**
-   * Avoid unnecessary operations on an {@link Optional} that ultimately result in that very same
-   * {@link Optional}.
-   */
+  /** Don't unnecessarily transform an {@link Optional} to an equivalent instance. */
   static final class OptionalIdentity<T> {
     @BeforeTemplate
     @SuppressWarnings("NestedOptionals")

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/PrimitiveRules.java

@@ -8,6 +8,8 @@ import com.google.common.primitives.Floats;
 import com.google.common.primitives.Ints;
 import com.google.common.primitives.Longs;
 import com.google.common.primitives.Shorts;
+import com.google.common.primitives.UnsignedInts;
+import com.google.common.primitives.UnsignedLongs;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.AlsoNegation;
@@ -76,6 +78,8 @@ final class PrimitiveRules {
   }
 
   /** Prefer {@link Math#toIntExact(long)} over the Guava alternative. */
+  // XXX: This rule changes the exception possibly thrown from `IllegalArgumentException` to
+  // `ArithmeticException`.
   static final class LongToIntExact {
     @BeforeTemplate
     int before(long l) {
@@ -192,97 +196,6 @@ final class PrimitiveRules {
     }
   }
 
-  /** Prefer {@link Boolean#compare(boolean, boolean)} over the Guava alternative. */
-  static final class BooleanCompare {
-    @BeforeTemplate
-    int before(boolean a, boolean b) {
-      return Booleans.compare(a, b);
-    }
-
-    @AfterTemplate
-    int after(boolean a, boolean b) {
-      return Boolean.compare(a, b);
-    }
-  }
-
-  /** Prefer {@link Character#compare(char, char)} over the Guava alternative. */
-  static final class CharacterCompare {
-    @BeforeTemplate
-    int before(char a, char b) {
-      return Chars.compare(a, b);
-    }
-
-    @AfterTemplate
-    int after(char a, char b) {
-      return Character.compare(a, b);
-    }
-  }
-
-  /** Prefer {@link Short#compare(short, short)} over the Guava alternative. */
-  static final class ShortCompare {
-    @BeforeTemplate
-    int before(short a, short b) {
-      return Shorts.compare(a, b);
-    }
-
-    @AfterTemplate
-    int after(short a, short b) {
-      return Short.compare(a, b);
-    }
-  }
-
-  /** Prefer {@link Integer#compare(int, int)} over the Guava alternative. */
-  static final class IntegerCompare {
-    @BeforeTemplate
-    int before(int a, int b) {
-      return Ints.compare(a, b);
-    }
-
-    @AfterTemplate
-    int after(int a, int b) {
-      return Integer.compare(a, b);
-    }
-  }
-
-  /** Prefer {@link Long#compare(long, long)} over the Guava alternative. */
-  static final class LongCompare {
-    @BeforeTemplate
-    int before(long a, long b) {
-      return Longs.compare(a, b);
-    }
-
-    @AfterTemplate
-    int after(long a, long b) {
-      return Long.compare(a, b);
-    }
-  }
-
-  /** Prefer {@link Float#compare(float, float)} over the Guava alternative. */
-  static final class FloatCompare {
-    @BeforeTemplate
-    int before(float a, float b) {
-      return Floats.compare(a, b);
-    }
-
-    @AfterTemplate
-    int after(float a, float b) {
-      return Float.compare(a, b);
-    }
-  }
-
-  /** Prefer {@link Double#compare(double, double)} over the Guava alternative. */
-  static final class DoubleCompare {
-    @BeforeTemplate
-    int before(double a, double b) {
-      return Doubles.compare(a, b);
-    }
-
-    @AfterTemplate
-    int after(double a, double b) {
-      return Double.compare(a, b);
-    }
-  }
-
   /** Prefer {@link Character#BYTES} over the Guava alternative. */
   static final class CharacterBytes {
     @BeforeTemplate
@@ -442,4 +355,205 @@ final class PrimitiveRules {
       return Long.signum(l) == -1;
     }
   }
+
+  /** Prefer JDK's {@link Integer#compareUnsigned(int, int)} over third-party alternatives. */
+  static final class IntegerCompareUnsigned {
+    @BeforeTemplate
+    int before(int x, int y) {
+      return UnsignedInts.compare(x, y);
+    }
+
+    @AfterTemplate
+    int after(int x, int y) {
+      return Integer.compareUnsigned(x, y);
+    }
+  }
+
+  /** Prefer JDK's {@link Long#compareUnsigned(long, long)} over third-party alternatives. */
+  static final class LongCompareUnsigned {
+    @BeforeTemplate
+    long before(long x, long y) {
+      return UnsignedLongs.compare(x, y);
+    }
+
+    @AfterTemplate
+    long after(long x, long y) {
+      return Long.compareUnsigned(x, y);
+    }
+  }
+
+  /** Prefer JDK's {@link Integer#divideUnsigned(int, int)} over third-party alternatives. */
+  static final class IntegerDivideUnsigned {
+    @BeforeTemplate
+    int before(int x, int y) {
+      return UnsignedInts.divide(x, y);
+    }
+
+    @AfterTemplate
+    int after(int x, int y) {
+      return Integer.divideUnsigned(x, y);
+    }
+  }
+
+  /** Prefer JDK's {@link Long#divideUnsigned(long, long)} over third-party alternatives. */
+  static final class LongDivideUnsigned {
+    @BeforeTemplate
+    long before(long x, long y) {
+      return UnsignedLongs.divide(x, y);
+    }
+
+    @AfterTemplate
+    long after(long x, long y) {
+      return Long.divideUnsigned(x, y);
+    }
+  }
+
+  /** Prefer JDK's {@link Integer#remainderUnsigned(int, int)} over third-party alternatives. */
+  static final class IntegerRemainderUnsigned {
+    @BeforeTemplate
+    int before(int x, int y) {
+      return UnsignedInts.remainder(x, y);
+    }
+
+    @AfterTemplate
+    int after(int x, int y) {
+      return Integer.remainderUnsigned(x, y);
+    }
+  }
+
+  /** Prefer JDK's {@link Long#remainderUnsigned(long, long)} over third-party alternatives. */
+  static final class LongRemainderUnsigned {
+    @BeforeTemplate
+    long before(long x, long y) {
+      return UnsignedLongs.remainder(x, y);
+    }
+
+    @AfterTemplate
+    long after(long x, long y) {
+      return Long.remainderUnsigned(x, y);
+    }
+  }
+
+  /**
+   * Prefer JDK's {@link Integer#parseUnsignedInt(String)} over third-party or more verbose
+   * alternatives.
+   */
+  static final class IntegerParseUnsignedInt {
+    @BeforeTemplate
+    int before(String string) {
+      return Refaster.anyOf(
+          UnsignedInts.parseUnsignedInt(string), Integer.parseUnsignedInt(string, 10));
+    }
+
+    @AfterTemplate
+    int after(String string) {
+      return Integer.parseUnsignedInt(string);
+    }
+  }
+
+  /**
+   * Prefer JDK's {@link Long#parseUnsignedLong(String)} over third-party or more verbose
+   * alternatives.
+   */
+  static final class LongParseUnsignedLong {
+    @BeforeTemplate
+    long before(String string) {
+      return Refaster.anyOf(
+          UnsignedLongs.parseUnsignedLong(string), Long.parseUnsignedLong(string, 10));
+    }
+
+    @AfterTemplate
+    long after(String string) {
+      return Long.parseUnsignedLong(string);
+    }
+  }
+
+  /** Prefer JDK's {@link Integer#parseUnsignedInt(String, int)} over third-party alternatives. */
+  static final class IntegerParseUnsignedIntWithRadix {
+    @BeforeTemplate
+    int before(String string, int radix) {
+      return UnsignedInts.parseUnsignedInt(string, radix);
+    }
+
+    @AfterTemplate
+    int after(String string, int radix) {
+      return Integer.parseUnsignedInt(string, radix);
+    }
+  }
+
+  /** Prefer JDK's {@link Long#parseUnsignedLong(String, int)} over third-party alternatives. */
+  static final class LongParseUnsignedLongWithRadix {
+    @BeforeTemplate
+    long before(String string, int radix) {
+      return UnsignedLongs.parseUnsignedLong(string, radix);
+    }
+
+    @AfterTemplate
+    long after(String string, int radix) {
+      return Long.parseUnsignedLong(string, radix);
+    }
+  }
+
+  /**
+   * Prefer JDK's {@link Integer#toUnsignedString(int)} over third-party or more verbose
+   * alternatives.
+   */
+  static final class IntegerToUnsignedString {
+    @BeforeTemplate
+    String before(int i) {
+      return Refaster.anyOf(UnsignedInts.toString(i), Integer.toUnsignedString(i, 10));
+    }
+
+    @AfterTemplate
+    String after(int i) {
+      return Integer.toUnsignedString(i);
+    }
+  }
+
+  /**
+   * Prefer JDK's {@link Long#toUnsignedString(long)} over third-party or more verbose alternatives.
+   */
+  static final class LongToUnsignedString {
+    @BeforeTemplate
+    String before(long i) {
+      return Refaster.anyOf(UnsignedLongs.toString(i), Long.toUnsignedString(i, 10));
+    }
+
+    @AfterTemplate
+    String after(long i) {
+      return Long.toUnsignedString(i);
+    }
+  }
+
+  /**
+   * Prefer JDK's {@link Integer#toUnsignedString(int,int)} over third-party or more verbose
+   * alternatives.
+   */
+  static final class IntegerToUnsignedStringWithRadix {
+    @BeforeTemplate
+    String before(int i, int radix) {
+      return UnsignedInts.toString(i, radix);
+    }
+
+    @AfterTemplate
+    String after(int i, int radix) {
+      return Integer.toUnsignedString(i, radix);
+    }
+  }
+
+  /**
+   * Prefer JDK's {@link Long#toUnsignedString(long,int)} over third-party or more verbose
+   * alternatives.
+   */
+  static final class LongToUnsignedStringWithRadix {
+    @BeforeTemplate
+    String before(long i, int radix) {
+      return UnsignedLongs.toString(i, radix);
+    }
+
+    @AfterTemplate
+    String after(long i, int radix) {
+      return Long.toUnsignedString(i, radix);
+    }
+  }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/ReactorRules.java

@@ -13,6 +13,7 @@ import static java.util.stream.Collectors.toCollection;
 import static org.assertj.core.api.Assertions.assertThat;
 import static reactor.function.TupleUtils.function;
 
+import com.github.benmanes.caffeine.cache.AsyncLoadingCache;
 import com.google.common.collect.ImmutableCollection;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
@@ -41,6 +42,7 @@ import java.util.function.Function;
 import java.util.function.Predicate;
 import java.util.function.Supplier;
 import java.util.stream.Collector;
+import java.util.stream.Stream;
 import org.jspecify.annotations.Nullable;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
@@ -1204,10 +1206,17 @@ final class ReactorRules {
   }
 
   /** Prefer {@link Flux#fromIterable(Iterable)} over less efficient alternatives. */
+  // XXX: Once the `FluxFromStreamSupplier` rule is constrained using
+  // `@NotMatches(IsIdentityOperation.class)`, this rule should also cover
+  // `Flux.fromStream(collection.stream())`.
   static final class FluxFromIterable<T> {
+    // XXX: Once the `MethodReferenceUsage` check is generally enabled, drop the second
+    // `Refaster.anyOf` variant.
     @BeforeTemplate
     Flux<T> before(Collection<T> collection) {
-      return Flux.fromStream(collection.stream());
+      return Flux.fromStream(
+          Refaster.<Supplier<Stream<? extends T>>>anyOf(
+              collection::stream, () -> collection.stream()));
     }
 
     @AfterTemplate
@@ -1759,6 +1768,60 @@ final class ReactorRules {
     }
   }
 
+  /**
+   * Prefer {@link StepVerifier#verify()} over a dangling {@link
+   * StepVerifier#verifyThenAssertThat()}.
+   */
+  // XXX: Application of this rule (and several others in this class) will cause invalid code if the
+  // result of the rewritten expression is dereferenced. Consider introducing a bug checker that
+  // identifies rules that change the return type of an expression and annotates them accordingly.
+  // The associated annotation can then be used to instruct an annotation processor to generate
+  // corresponding `void` rules that match only statements. This would allow the `Refaster` check to
+  // conditionally skip "not fully safe" rules. This allows conditionally flagging more dubious
+  // code, at the risk of compilation failures. With this rule, for example, we want to explicitly
+  // nudge users towards `StepVerifier.Step#assertNext(Consumer)` or
+  // `StepVerifier.Step#expectNext(Object)`, together with `Step#verifyComplete()`.
+  static final class StepVerifierVerify {
+    @BeforeTemplate
+    StepVerifier.Assertions before(StepVerifier stepVerifier) {
+      return stepVerifier.verifyThenAssertThat();
+    }
+
+    @AfterTemplate
+    Duration after(StepVerifier stepVerifier) {
+      return stepVerifier.verify();
+    }
+  }
+
+  /**
+   * Prefer {@link StepVerifier#verify(Duration)} over a dangling {@link
+   * StepVerifier#verifyThenAssertThat(Duration)}.
+   */
+  static final class StepVerifierVerifyDuration {
+    @BeforeTemplate
+    StepVerifier.Assertions before(StepVerifier stepVerifier, Duration duration) {
+      return stepVerifier.verifyThenAssertThat(duration);
+    }
+
+    @AfterTemplate
+    Duration after(StepVerifier stepVerifier, Duration duration) {
+      return stepVerifier.verify(duration);
+    }
+  }
+
+  /** Don't unnecessarily invoke {@link StepVerifier#verifyLater()} multiple times. */
+  static final class StepVerifierVerifyLater {
+    @BeforeTemplate
+    StepVerifier before(StepVerifier stepVerifier) {
+      return stepVerifier.verifyLater().verifyLater();
+    }
+
+    @AfterTemplate
+    StepVerifier after(StepVerifier stepVerifier) {
+      return stepVerifier.verifyLater();
+    }
+  }
+
   /** Don't unnecessarily have {@link StepVerifier.Step} expect no elements. */
   static final class StepVerifierStepIdentity<T> {
     @BeforeTemplate
@@ -1859,6 +1922,12 @@ final class ReactorRules {
       return step.expectErrorMatches(predicate).verify();
     }
 
+    @BeforeTemplate
+    @SuppressWarnings("StepVerifierVerify" /* This is a more specific template. */)
+    StepVerifier.Assertions before2(StepVerifier.LastStep step, Predicate<Throwable> predicate) {
+      return step.expectError().verifyThenAssertThat().hasOperatorErrorMatching(predicate);
+    }
+
     @AfterTemplate
     Duration after(StepVerifier.LastStep step, Predicate<Throwable> predicate) {
       return step.verifyErrorMatches(predicate);
@@ -1881,6 +1950,30 @@ final class ReactorRules {
     }
   }
 
+  /**
+   * Prefer {@link StepVerifier.LastStep#verifyErrorSatisfies(Consumer)} with AssertJ over more
+   * contrived alternatives.
+   */
+  static final class StepVerifierLastStepVerifyErrorSatisfiesAssertJ<T extends Throwable> {
+    @BeforeTemplate
+    @SuppressWarnings("StepVerifierVerify" /* This is a more specific template. */)
+    StepVerifier.Assertions before(StepVerifier.LastStep step, Class<T> clazz, String message) {
+      return Refaster.anyOf(
+          step.expectError()
+              .verifyThenAssertThat()
+              .hasOperatorErrorOfType(clazz)
+              .hasOperatorErrorWithMessage(message),
+          step.expectError(clazz).verifyThenAssertThat().hasOperatorErrorWithMessage(message),
+          step.expectErrorMessage(message).verifyThenAssertThat().hasOperatorErrorOfType(clazz));
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    Duration after(StepVerifier.LastStep step, Class<T> clazz, String message) {
+      return step.verifyErrorSatisfies(t -> assertThat(t).isInstanceOf(clazz).hasMessage(message));
+    }
+  }
+
   /**
    * Prefer {@link StepVerifier.LastStep#verifyErrorMessage(String)} over more verbose alternatives.
    */
@@ -1913,7 +2006,7 @@ final class ReactorRules {
 
   /**
    * Prefer {@link Mono#fromFuture(Supplier)} over {@link Mono#fromFuture(CompletableFuture)}, as
-   * the former may defer initiation of the asynchornous computation until subscription.
+   * the former may defer initiation of the asynchronous computation until subscription.
    */
   static final class MonoFromFutureSupplier<T> {
     // XXX: Constrain the `future` parameter using `@NotMatches(IsIdentityOperation.class)` once
@@ -1932,7 +2025,7 @@ final class ReactorRules {
   /**
    * Prefer {@link Mono#fromFuture(Supplier, boolean)} over {@link
    * Mono#fromFuture(CompletableFuture, boolean)}, as the former may defer initiation of the
-   * asynchornous computation until subscription.
+   * asynchronous computation until subscription.
    */
   static final class MonoFromFutureSupplierBoolean<T> {
     // XXX: Constrain the `future` parameter using `@NotMatches(IsIdentityOperation.class)` once
@@ -1947,4 +2040,39 @@ final class ReactorRules {
       return Mono.fromFuture(() -> future, suppressCancel);
     }
   }
+
+  /**
+   * Don't propagate {@link Mono} cancellations to an upstream cache value computation, as
+   * completion of such computations may benefit concurrent or subsequent cache usages.
+   */
+  static final class MonoFromFutureAsyncLoadingCacheGet<K, V> {
+    @BeforeTemplate
+    Mono<V> before(AsyncLoadingCache<K, V> cache, K key) {
+      return Mono.fromFuture(() -> cache.get(key));
+    }
+
+    @AfterTemplate
+    Mono<V> after(AsyncLoadingCache<K, V> cache, K key) {
+      return Mono.fromFuture(() -> cache.get(key), /* suppressCancel= */ true);
+    }
+  }
+
+  /**
+   * Prefer {@link Flux#fromStream(Supplier)} over {@link Flux#fromStream(Stream)}, as the former
+   * yields a {@link Flux} that is more likely to behave as expected when subscribed to more than
+   * once.
+   */
+  static final class FluxFromStreamSupplier<T> {
+    // XXX: Constrain the `stream` parameter using `@NotMatches(IsIdentityOperation.class)` once
+    // `IsIdentityOperation` no longer matches nullary method invocations.
+    @BeforeTemplate
+    Flux<T> before(Stream<T> stream) {
+      return Flux.fromStream(stream);
+    }
+
+    @AfterTemplate
+    Flux<T> after(Stream<T> stream) {
+      return Flux.fromStream(() -> stream);
+    }
+  }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/StringRules.java

@@ -244,4 +244,105 @@ final class StringRules {
       return Utf8.encodedLength(str);
     }
   }
+
+  /** Prefer {@link String#indexOf(int, int)} over less efficient alternatives. */
+  static final class StringIndexOfChar {
+    @BeforeTemplate
+    @SuppressWarnings("java:S4635" /* This violation will be rewritten. */)
+    int before(String string, int ch, int fromIndex) {
+      return string.substring(fromIndex).indexOf(ch);
+    }
+
+    @AfterTemplate
+    int after(String string, int ch, int fromIndex) {
+      return Math.max(-1, string.indexOf(ch, fromIndex) - fromIndex);
+    }
+  }
+
+  /** Prefer {@link String#indexOf(String, int)} over less efficient alternatives. */
+  static final class StringIndexOfString {
+    @BeforeTemplate
+    @SuppressWarnings("java:S4635" /* This violation will be rewritten. */)
+    int before(String string, String substring, int fromIndex) {
+      return string.substring(fromIndex).indexOf(substring);
+    }
+
+    @AfterTemplate
+    int after(String string, String substring, int fromIndex) {
+      return Math.max(-1, string.indexOf(substring, fromIndex) - fromIndex);
+    }
+  }
+
+  // XXX: Once we compile Refaster templates with JDK 21 also suggest `String#indexOf(int, int,
+  // int)` and `String#indexOf(String, int, int)`.
+
+  /** Prefer {@link String#lastIndexOf(int, int)} over less efficient alternatives. */
+  static final class StringLastIndexOfChar {
+    @BeforeTemplate
+    @SuppressWarnings("java:S4635" /* This violation will be rewritten. */)
+    int before(String string, int ch, int fromIndex) {
+      return string.substring(fromIndex).lastIndexOf(ch);
+    }
+
+    @AfterTemplate
+    int after(String string, int ch, int fromIndex) {
+      return Math.max(-1, string.lastIndexOf(ch) - fromIndex);
+    }
+  }
+
+  /** Prefer {@link String#lastIndexOf(String, int)} over less efficient alternatives. */
+  static final class StringLastIndexOfString {
+    @BeforeTemplate
+    @SuppressWarnings("java:S4635" /* This violation will be rewritten. */)
+    int before(String string, String substring, int fromIndex) {
+      return string.substring(fromIndex).lastIndexOf(substring);
+    }
+
+    @AfterTemplate
+    int after(String string, String substring, int fromIndex) {
+      return Math.max(-1, string.lastIndexOf(substring) - fromIndex);
+    }
+  }
+
+  /** Prefer {@link String#lastIndexOf(int, int)} over less efficient alternatives. */
+  static final class StringLastIndexOfCharWithIndex {
+    @BeforeTemplate
+    int before(String string, int ch, int fromIndex) {
+      return string.substring(0, fromIndex).lastIndexOf(ch);
+    }
+
+    @AfterTemplate
+    int after(String string, int ch, int fromIndex) {
+      return string.lastIndexOf(ch, fromIndex - 1);
+    }
+  }
+
+  /** Prefer {@link String#lastIndexOf(String, int)} over less efficient alternatives. */
+  // XXX: The replacement expression isn't fully equivalent: in case `substring` is empty, then
+  // the replacement yields `fromIndex - 1` rather than `fromIndex`.
+  static final class StringLastIndexOfStringWithIndex {
+    @BeforeTemplate
+    int before(String string, String substring, int fromIndex) {
+      return string.substring(0, fromIndex).lastIndexOf(substring);
+    }
+
+    @AfterTemplate
+    int after(String string, String substring, int fromIndex) {
+      return string.lastIndexOf(substring, fromIndex - 1);
+    }
+  }
+
+  /** Prefer {@link String#startsWith(String, int)} over less efficient alternatives. */
+  static final class StringStartsWith {
+    @BeforeTemplate
+    @SuppressWarnings("java:S4635" /* This violation will be rewritten. */)
+    boolean before(String string, String prefix, int fromIndex) {
+      return string.substring(fromIndex).startsWith(prefix);
+    }
+
+    @AfterTemplate
+    boolean after(String string, String prefix, int fromIndex) {
+      return string.startsWith(prefix, fromIndex);
+    }
+  }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/TimeRules.java

@@ -142,6 +142,63 @@ final class TimeRules {
     }
   }
 
+  /** Don't unnecessarily transform an {@link Instant} to an equivalent instance. */
+  static final class InstantIdentity {
+    @BeforeTemplate
+    Instant before(Instant instant, TemporalUnit temporalUnit) {
+      return Refaster.anyOf(
+          instant.plus(Duration.ZERO),
+          instant.plus(0, temporalUnit),
+          instant.plusNanos(0),
+          instant.plusMillis(0),
+          instant.plusSeconds(0),
+          instant.minus(Duration.ZERO),
+          instant.minus(0, temporalUnit),
+          instant.minusNanos(0),
+          instant.minusMillis(0),
+          instant.minusSeconds(0),
+          Instant.parse(instant.toString()),
+          instant.truncatedTo(ChronoUnit.NANOS),
+          Instant.ofEpochSecond(instant.getEpochSecond(), instant.getNano()));
+    }
+
+    @AfterTemplate
+    Instant after(Instant instant) {
+      return instant;
+    }
+  }
+
+  /**
+   * Prefer {@link Instant#truncatedTo(TemporalUnit)} over less obvious alternatives.
+   *
+   * <p>Note that {@link Instant#toEpochMilli()} throws an {@link ArithmeticException} for dates
+   * very far in the past or future, while the suggested alternative doesn't.
+   */
+  static final class InstantTruncatedToMilliseconds {
+    @BeforeTemplate
+    Instant before(Instant instant) {
+      return Instant.ofEpochMilli(instant.toEpochMilli());
+    }
+
+    @AfterTemplate
+    Instant after(Instant instant) {
+      return instant.truncatedTo(ChronoUnit.MILLIS);
+    }
+  }
+
+  /** Prefer {@link Instant#truncatedTo(TemporalUnit)} over less obvious alternatives. */
+  static final class InstantTruncatedToSeconds {
+    @BeforeTemplate
+    Instant before(Instant instant) {
+      return Instant.ofEpochSecond(instant.getEpochSecond());
+    }
+
+    @AfterTemplate
+    Instant after(Instant instant) {
+      return instant.truncatedTo(ChronoUnit.SECONDS);
+    }
+  }
+
   /** Prefer {@link Instant#atOffset(ZoneOffset)} over more verbose alternatives. */
   static final class InstantAtOffset {
     @BeforeTemplate

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

@@ -0,0 +1,70 @@
+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 ClassCastLambdaUsageTest {
+  @Test
+  void identification() {
+    CompilationTestHelper.newInstance(ClassCastLambdaUsage.class, getClass())
+        .addSourceLines(
+            "A.java",
+            "import com.google.common.collect.ImmutableSet;",
+            "import java.util.stream.IntStream;",
+            "import java.util.stream.Stream;",
+            "",
+            "class A {",
+            "  void m() {",
+            "    Number localVariable = 0;",
+            "",
+            "    Stream.of(0).map(i -> i);",
+            "    Stream.of(1).map(i -> i + 1);",
+            "    Stream.of(2).map(Integer.class::cast);",
+            "    Stream.of(3).map(i -> (Integer) 2);",
+            "    Stream.of(4).map(i -> (Integer) localVariable);",
+            "    // XXX: Ideally this case is also flagged. Pick this up in the context of merging the",
+            "    // `ClassCastLambdaUsage` and `MethodReferenceUsage` checks, or introduce a separate check that",
+            "    // simplifies unnecessary block lambda expressions.",
+            "    Stream.of(5)",
+            "        .map(",
+            "            i -> {",
+            "              return (Integer) i;",
+            "            });",
+            "    Stream.<ImmutableSet>of(ImmutableSet.of(5)).map(s -> (ImmutableSet<Number>) s);",
+            "    Stream.of(ImmutableSet.of(6)).map(s -> (ImmutableSet<?>) s);",
+            "    Stream.of(7).reduce((a, b) -> (Integer) a);",
+            "    IntStream.of(8).mapToObj(i -> (char) i);",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    Stream.of(8).map(i -> (Integer) i);",
+            "  }",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  void replacement() {
+    BugCheckerRefactoringTestHelper.newInstance(ClassCastLambdaUsage.class, getClass())
+        .addInputLines(
+            "A.java",
+            "import java.util.stream.Stream;",
+            "",
+            "class A {",
+            "  void m() {",
+            "    Stream.of(1).map(i -> (Integer) i);",
+            "  }",
+            "}")
+        .addOutputLines(
+            "A.java",
+            "import java.util.stream.Stream;",
+            "",
+            "class A {",
+            "  void m() {",
+            "    Stream.of(1).map(Integer.class::cast);",
+            "  }",
+            "}")
+        .doTest(TestMode.TEXT_MATCH);
+  }
+}

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

@@ -0,0 +1,78 @@
+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 ConstantNamingTest {
+  @Test
+  void identification() {
+    CompilationTestHelper.newInstance(ConstantNaming.class, getClass())
+        .addSourceLines(
+            "A.java",
+            "class A {",
+            "  private static final long serialVersionUID = 1L;",
+            "  private static final int FOO = 1;",
+            "  // BUG: Diagnostic contains: consider renaming to 'BAR', though note that this is not a private",
+            "  // constant",
+            "  static final int bar = 2;",
+            "  // BUG: Diagnostic contains:",
+            "  private static final int baz = 3;",
+            "  // BUG: Diagnostic contains: consider renaming to 'QUX_QUUX', though note that a variable with",
+            "  // this name is already declared",
+            "  private static final int qux_QUUX = 4;",
+            "  // BUG: Diagnostic contains: consider renaming to 'QUUZ', though note that a variable with",
+            "  // this name is already declared",
+            "  private static final int quuz = 3;",
+            "",
+            "  private final int foo = 4;",
+            "  private final Runnable QUX_QUUX =",
+            "      new Runnable() {",
+            "        private static final int QUUZ = 1;",
+            "",
+            "        @Override",
+            "        public void run() {}",
+            "      };",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  void identificationWithCustomExemption() {
+    CompilationTestHelper.newInstance(ConstantNaming.class, getClass())
+        .setArgs("-XepOpt:CanonicalConstantNaming:ExemptedNames=foo,baz")
+        .addSourceLines(
+            "A.java",
+            "class A {",
+            "  private static final long serialVersionUID = 1L;",
+            "  private static final int foo = 1;",
+            "  // BUG: Diagnostic contains:",
+            "  private static final int bar = 2;",
+            "  private static final int baz = 3;",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  void replacement() {
+    BugCheckerRefactoringTestHelper.newInstance(ConstantNaming.class, getClass())
+        .addInputLines(
+            "A.java",
+            "class A {",
+            "  static final int foo = 1;",
+            "  private static final int bar = 2;",
+            "  private static final int baz = 3;",
+            "  private static final int BAZ = 4;",
+            "}")
+        .addOutputLines(
+            "A.java",
+            "class A {",
+            "  static final int foo = 1;",
+            "  private static final int BAR = 2;",
+            "  private static final int baz = 3;",
+            "  private static final int BAZ = 4;",
+            "}")
+        .doTest(TestMode.TEXT_MATCH);
+  }
+}

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

@@ -28,6 +28,8 @@ final class IdentityConversionTest {
             "import com.google.common.collect.ImmutableTable;",
             "import com.google.errorprone.matchers.Matcher;",
             "import com.google.errorprone.matchers.Matchers;",
+            "import java.time.Instant;",
+            "import java.time.ZonedDateTime;",
             "import reactor.adapter.rxjava.RxJava2Adapter;",
             "import reactor.core.publisher.Flux;",
             "import reactor.core.publisher.Mono;",
@@ -149,6 +151,10 @@ final class IdentityConversionTest {
             "    // BUG: Diagnostic contains:",
             "    ImmutableTable<Object, Object, Object> o11 = ImmutableTable.copyOf(ImmutableTable.of());",
             "",
+            "    Instant instant1 = Instant.from(ZonedDateTime.now());",
+            "    // BUG: Diagnostic contains:",
+            "    Instant instant2 = Instant.from(Instant.now());",
+            "",
             "    // BUG: Diagnostic contains:",
             "    Matcher allOf1 = Matchers.allOf(instanceMethod());",
             "    Matcher allOf2 = Matchers.allOf(instanceMethod(), staticMethod());",

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

@@ -18,22 +18,23 @@ final class IsInstanceLambdaUsageTest {
             "  void m() {",
             "    Integer localVariable = 0;",
             "",
-            "    Stream.of(0).map(i -> i + 1);",
-            "    Stream.of(1).filter(Integer.class::isInstance);",
-            "    Stream.of(2).filter(i -> i.getClass() instanceof Class);",
-            "    Stream.of(3).filter(i -> localVariable instanceof Integer);",
+            "    Stream.of(0).map(i -> i);",
+            "    Stream.of(1).map(i -> i + 1);",
+            "    Stream.of(2).filter(Integer.class::isInstance);",
+            "    Stream.of(3).filter(i -> i.getClass() instanceof Class);",
+            "    Stream.of(4).filter(i -> localVariable instanceof Integer);",
             "    // XXX: Ideally this case is also flagged. Pick this up in the context of merging the",
             "    // `IsInstanceLambdaUsage` and `MethodReferenceUsage` checks, or introduce a separate check that",
             "    // simplifies unnecessary block lambda expressions.",
-            "    Stream.of(4)",
+            "    Stream.of(5)",
             "        .filter(",
             "            i -> {",
-            "              return localVariable instanceof Integer;",
+            "              return i instanceof Integer;",
             "            });",
-            "    Flux.just(5, \"foo\").distinctUntilChanged(v -> v, (a, b) -> a instanceof Integer);",
+            "    Flux.just(6, \"foo\").distinctUntilChanged(v -> v, (a, b) -> a instanceof Integer);",
             "",
             "    // BUG: Diagnostic contains:",
-            "    Stream.of(6).filter(i -> i instanceof Integer);",
+            "    Stream.of(7).filter(i -> i instanceof Integer);",
             "  }",
             "}")
         .doTest();

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

@@ -29,6 +29,10 @@ final class LexicographicalAnnotationAttributeListingTest {
             "  @interface Foo {",
             "    String[] value() default {};",
             "",
+            "    boolean[] bools() default {};",
+            "",
+            "    char[] chars() default {};",
+            "",
             "    int[] ints() default {};",
             "",
             "    Class<?>[] cls() default {};",
@@ -69,6 +73,32 @@ final class LexicographicalAnnotationAttributeListingTest {
             "  @Foo({\"a\", \"A\"})",
             "  A unsortedStringCaseInsensitiveWithTotalOrderFallback();",
             "",
+            "  @Foo(bools = {})",
+            "  A noBools();",
+            "",
+            "  @Foo(bools = {false})",
+            "  A oneBool();",
+            "",
+            "  @Foo(bools = {false, true})",
+            "  A sortedBools();",
+            "",
+            "  // BUG: Diagnostic contains:",
+            "  @Foo(bools = {true, false})",
+            "  A unsortedBools();",
+            "",
+            "  @Foo(chars = {})",
+            "  A noChars();",
+            "",
+            "  @Foo(chars = {'a'})",
+            "  A oneChar();",
+            "",
+            "  @Foo(chars = {'a', 'b'})",
+            "  A sortedChars();",
+            "",
+            "  // BUG: Diagnostic contains:",
+            "  @Foo(chars = {'b', 'a'})",
+            "  A unsortedChars();",
+            "",
             "  @Foo(ints = {})",
             "  A noInts();",
             "",
@@ -173,6 +203,10 @@ final class LexicographicalAnnotationAttributeListingTest {
             "  @interface Foo {",
             "    String[] value() default {};",
             "",
+            "    boolean[] bools() default {};",
+            "",
+            "    char[] chars() default {};",
+            "",
             "    Class<?>[] cls() default {};",
             "",
             "    RoundingMode[] enums() default {};",
@@ -185,7 +219,13 @@ final class LexicographicalAnnotationAttributeListingTest {
             "  }",
             "",
             "  @Foo({\" \", \"\", \"b\", \"a\"})",
-            "  A unsortedString();",
+            "  A unsortedStrings();",
+            "",
+            "  @Foo(bools = {true, false})",
+            "  A unsortedBooleans();",
+            "",
+            "  @Foo(chars = {'b', 'a'})",
+            "  A unsortedChars();",
             "",
             "  @Foo(cls = {long.class, int.class})",
             "  A unsortedClasses();",
@@ -210,6 +250,10 @@ final class LexicographicalAnnotationAttributeListingTest {
             "  @interface Foo {",
             "    String[] value() default {};",
             "",
+            "    boolean[] bools() default {};",
+            "",
+            "    char[] chars() default {};",
+            "",
             "    Class<?>[] cls() default {};",
             "",
             "    RoundingMode[] enums() default {};",
@@ -222,7 +266,13 @@ final class LexicographicalAnnotationAttributeListingTest {
             "  }",
             "",
             "  @Foo({\"\", \" \", \"a\", \"b\"})",
-            "  A unsortedString();",
+            "  A unsortedStrings();",
+            "",
+            "  @Foo(bools = {false, true})",
+            "  A unsortedBooleans();",
+            "",
+            "  @Foo(chars = {'a', 'b'})",
+            "  A unsortedChars();",
             "",
             "  @Foo(cls = {int.class, long.class})",
             "  A unsortedClasses();",

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

@@ -5,14 +5,15 @@ import com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode;
 import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
-final class OptionalOrElseTest {
+final class OptionalOrElseGetTest {
   @Test
   void identification() {
-    CompilationTestHelper.newInstance(OptionalOrElse.class, getClass())
+    CompilationTestHelper.newInstance(OptionalOrElseGet.class, getClass())
         .addSourceLines(
             "A.java",
             "import com.google.errorprone.refaster.Refaster;",
             "import java.util.Optional;",
+            "import java.util.function.Supplier;",
             "",
             "class A {",
             "  private final Optional<Object> optional = Optional.empty();",
@@ -27,6 +28,7 @@ final class OptionalOrElseTest {
             "    optional.orElse(string);",
             "    optional.orElse(this.string);",
             "    optional.orElse(Refaster.anyOf(\"constant\", \"another\"));",
+            "    Optional.<Supplier<String>>empty().orElse(() -> \"constant\");",
             "",
             "    // BUG: Diagnostic contains:",
             "    Optional.empty().orElse(string + \"constant\");",
@@ -67,7 +69,7 @@ final class OptionalOrElseTest {
 
   @Test
   void replacement() {
-    BugCheckerRefactoringTestHelper.newInstance(OptionalOrElse.class, getClass())
+    BugCheckerRefactoringTestHelper.newInstance(OptionalOrElseGet.class, getClass())
         .addInputLines(
             "A.java",
             "import java.util.Optional;",

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

@@ -0,0 +1,90 @@
+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 RedundantStringEscapeTest {
+  @Test
+  void identification() {
+    CompilationTestHelper.newInstance(RedundantStringEscape.class, getClass())
+        .addSourceLines(
+            "A.java",
+            "import java.util.Arrays;",
+            "import java.util.List;",
+            "",
+            "class A {",
+            "  List<String> m() {",
+            "    return Arrays.asList(",
+            "        \"foo\",",
+            "        \"ß\",",
+            "        \"'\",",
+            "        \"\\\"\",",
+            "        \"\\\\\",",
+            "        \"\\\\'\",",
+            "        \"'\\\\\",",
+            "        // BUG: Diagnostic contains:",
+            "        \"\\\\\\'\",",
+            "        // BUG: Diagnostic contains:",
+            "        \"\\'\\\\\",",
+            "        // BUG: Diagnostic contains:",
+            "        \"\\'\",",
+            "        // BUG: Diagnostic contains:",
+            "        \"'\\'\",",
+            "        // BUG: Diagnostic contains:",
+            "        \"\\''\",",
+            "        // BUG: Diagnostic contains:",
+            "        \"\\'\\'\",",
+            "        (",
+            "        // BUG: Diagnostic contains:",
+            "        /* Leading comment. */ \"\\'\" /* Trailing comment. */),",
+            "        // BUG: Diagnostic contains:",
+            "        \"\\'foo\\\"bar\\'baz\\\"qux\\'\");",
+            "  }",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  void replacement() {
+    BugCheckerRefactoringTestHelper.newInstance(RedundantStringEscape.class, getClass())
+        .addInputLines(
+            "A.java",
+            "import java.util.Arrays;",
+            "import java.util.List;",
+            "",
+            "class A {",
+            "  List<String> m() {",
+            "    return Arrays.asList(",
+            "        \"\\'\",",
+            "        \"'\\'\",",
+            "        \"\\''\",",
+            "        \"\\'\\'\",",
+            "        \"\\'ß\\'\",",
+            "        (",
+            "        /* Leading comment. */ \"\\'\" /* Trailing comment. */),",
+            "        \"\\'foo\\\"bar\\'baz\\\"qux\\'\");",
+            "  }",
+            "}")
+        .addOutputLines(
+            "A.java",
+            "import java.util.Arrays;",
+            "import java.util.List;",
+            "",
+            "class A {",
+            "  List<String> m() {",
+            "    return Arrays.asList(",
+            "        \"'\",",
+            "        \"''\",",
+            "        \"''\",",
+            "        \"''\",",
+            "        \"'ß'\",",
+            "        (",
+            "        /* Leading comment. */ \"'\" /* Trailing comment. */),",
+            "        \"'foo\\\"bar'baz\\\"qux'\");",
+            "  }",
+            "}")
+        .doTest(TestMode.TEXT_MATCH);
+  }
+}

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/Slf4jLoggerDeclarationTest.java

@@ -0,0 +1,218 @@
+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 Slf4jLoggerDeclarationTest {
+  @Test
+  void identification() {
+    CompilationTestHelper.newInstance(Slf4jLoggerDeclaration.class, getClass())
+        .addSourceLines(
+            "A.java",
+            "import static java.lang.Class.forName;",
+            "",
+            "import org.slf4j.Logger;",
+            "import org.slf4j.LoggerFactory;",
+            "",
+            "class A {",
+            "  private static final long serialVersionUID = 1L;",
+            "  private static final Logger LOG = LoggerFactory.getLogger(A.class);",
+            "",
+            "  abstract static class DynamicLogger {",
+            "    private final Logger log = LoggerFactory.getLogger(getClass());",
+            "  }",
+            "",
+            "  abstract static class DynamicLoggerWithExplicitThis {",
+            "    private final Logger log = LoggerFactory.getLogger(this.getClass());",
+            "  }",
+            "",
+            "  static final class StaticLogger {",
+            "    private static final Logger LOG = LoggerFactory.getLogger(StaticLogger.class);",
+            "  }",
+            "",
+            "  static final class StaticLoggerWithCustomIdentifier {",
+            "    private static final Logger LOG = LoggerFactory.getLogger(\"custom-identifier\");",
+            "  }",
+            "",
+            "  interface StaticLoggerForInterface {",
+            "    Logger LOG = LoggerFactory.getLogger(StaticLoggerForInterface.class);",
+            "  }",
+            "",
+            "  abstract static class DynamicLoggerForWrongTypeWithoutReceiver {",
+            "    // BUG: Diagnostic contains:",
+            "    private final Logger log = LoggerFactory.getLogger(forName(\"A.class\"));",
+            "",
+            "    DynamicLoggerForWrongTypeWithoutReceiver() throws ClassNotFoundException {}",
+            "  }",
+            "",
+            "  abstract static class DynamicLoggerForWrongTypeWithoutSymbol {",
+            "    // BUG: Diagnostic contains:",
+            "    private final Logger log = LoggerFactory.getLogger(\"foo\".getClass());",
+            "  }",
+            "",
+            "  abstract static class DynamicLoggerForWrongTypeWithSymbol {",
+            "    // BUG: Diagnostic contains:",
+            "    private final Logger log = LoggerFactory.getLogger(new A().getClass());",
+            "  }",
+            "",
+            "  static final class NonAbstractDynamicLogger {",
+            "    // BUG: Diagnostic contains:",
+            "    private final Logger log = LoggerFactory.getLogger(getClass());",
+            "  }",
+            "",
+            "  abstract static class DynamicLoggerWithMissingModifier {",
+            "    // BUG: Diagnostic contains:",
+            "    final Logger log = LoggerFactory.getLogger(getClass());",
+            "  }",
+            "",
+            "  abstract static class DynamicLoggerWithExcessModifier {",
+            "    // BUG: Diagnostic contains:",
+            "    private final transient Logger log = LoggerFactory.getLogger(getClass());",
+            "  }",
+            "",
+            "  abstract static class MisnamedDynamicLogger {",
+            "    // BUG: Diagnostic contains:",
+            "    private final Logger LOG = LoggerFactory.getLogger(getClass());",
+            "  }",
+            "",
+            "  static final class StaticLoggerWithMissingModifier {",
+            "    // BUG: Diagnostic contains:",
+            "    static final Logger LOG = LoggerFactory.getLogger(StaticLoggerWithMissingModifier.class);",
+            "  }",
+            "",
+            "  static final class StaticLoggerWithExcessModifier {",
+            "    // BUG: Diagnostic contains:",
+            "    private static final transient Logger LOG =",
+            "        LoggerFactory.getLogger(StaticLoggerWithExcessModifier.class);",
+            "  }",
+            "",
+            "  static final class MisnamedStaticLogger {",
+            "    // BUG: Diagnostic contains:",
+            "    private static final Logger log = LoggerFactory.getLogger(MisnamedStaticLogger.class);",
+            "  }",
+            "",
+            "  static final class StaticLoggerWithIncorrectIdentifier {",
+            "    // BUG: Diagnostic contains:",
+            "    private static final Logger LOG = LoggerFactory.getLogger(A.class);",
+            "  }",
+            "",
+            "  static final class StaticLoggerWithCustomIdentifierAndMissingModifier {",
+            "    // BUG: Diagnostic contains:",
+            "    static final Logger LOG = LoggerFactory.getLogger(\"custom-identifier\");",
+            "  }",
+            "",
+            "  static final class StaticLoggerWithCustomIdentifierAndExcessModifier {",
+            "    // BUG: Diagnostic contains:",
+            "    private static final transient Logger LOG = LoggerFactory.getLogger(\"custom-identifier\");",
+            "  }",
+            "",
+            "  static final class MisnamedStaticLoggerWithCustomIdentifier {",
+            "    // BUG: Diagnostic contains:",
+            "    private static final Logger log = LoggerFactory.getLogger(\"custom-identifier\");",
+            "  }",
+            "",
+            "  interface StaticLoggerForInterfaceWithExcessModifier {",
+            "    // BUG: Diagnostic contains:",
+            "    static Logger LOG = LoggerFactory.getLogger(StaticLoggerForInterfaceWithExcessModifier.class);",
+            "  }",
+            "",
+            "  interface MisnamedStaticLoggerForInterface {",
+            "    // BUG: Diagnostic contains:",
+            "    Logger log = LoggerFactory.getLogger(MisnamedStaticLoggerForInterface.class);",
+            "  }",
+            "",
+            "  interface StaticLoggerForInterfaceWithIncorrectIdentifier {",
+            "    // BUG: Diagnostic contains:",
+            "    Logger LOG = LoggerFactory.getLogger(A.class);",
+            "  }",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  void replacement() {
+    BugCheckerRefactoringTestHelper.newInstance(Slf4jLoggerDeclaration.class, getClass())
+        .addInputLines(
+            "A.java",
+            "import org.slf4j.Logger;",
+            "import org.slf4j.LoggerFactory;",
+            "",
+            "class A {",
+            "  static Logger foo = LoggerFactory.getLogger(Logger.class);",
+            "",
+            "  abstract static class DynamicLogger {",
+            "    transient Logger BAR = LoggerFactory.getLogger(getClass());",
+            "  }",
+            "",
+            "  static final class StaticLogger {",
+            "    transient Logger baz = LoggerFactory.getLogger(LoggerFactory.class);",
+            "  }",
+            "",
+            "  static final class StaticLoggerWithCustomIdentifier {",
+            "    transient Logger qux = LoggerFactory.getLogger(\"custom-identifier\");",
+            "  }",
+            "",
+            "  interface StaticLoggerForInterface {",
+            "    public static final Logger quux = LoggerFactory.getLogger(A.class);",
+            "  }",
+            "}")
+        .addOutputLines(
+            "A.java",
+            "import org.slf4j.Logger;",
+            "import org.slf4j.LoggerFactory;",
+            "",
+            "class A {",
+            "  private static final Logger LOG = LoggerFactory.getLogger(A.class);",
+            "",
+            "  abstract static class DynamicLogger {",
+            "    private final Logger log = LoggerFactory.getLogger(getClass());",
+            "  }",
+            "",
+            "  static final class StaticLogger {",
+            "    private static final Logger LOG = LoggerFactory.getLogger(StaticLogger.class);",
+            "  }",
+            "",
+            "  static final class StaticLoggerWithCustomIdentifier {",
+            "    private static final Logger LOG = LoggerFactory.getLogger(\"custom-identifier\");",
+            "  }",
+            "",
+            "  interface StaticLoggerForInterface {",
+            "    Logger LOG = LoggerFactory.getLogger(StaticLoggerForInterface.class);",
+            "  }",
+            "}")
+        .doTest(TestMode.TEXT_MATCH);
+  }
+
+  @Test
+  void replacementWithCustomLoggerName() {
+    BugCheckerRefactoringTestHelper.newInstance(Slf4jLoggerDeclaration.class, getClass())
+        .setArgs("-XepOpt:Slf4jLoggerDeclaration:CanonicalStaticLoggerName=FOO_BAR")
+        .addInputLines(
+            "A.java",
+            "import org.slf4j.Logger;",
+            "import org.slf4j.LoggerFactory;",
+            "",
+            "class A {",
+            "  transient Logger LOG = LoggerFactory.getLogger(Logger.class);",
+            "",
+            "  abstract static class DynamicLogger {",
+            "    transient Logger log = LoggerFactory.getLogger(getClass());",
+            "  }",
+            "}")
+        .addOutputLines(
+            "A.java",
+            "import org.slf4j.Logger;",
+            "import org.slf4j.LoggerFactory;",
+            "",
+            "class A {",
+            "  private static final Logger FOO_BAR = LoggerFactory.getLogger(A.class);",
+            "",
+            "  abstract static class DynamicLogger {",
+            "    private final Logger fooBar = LoggerFactory.getLogger(getClass());",
+            "  }",
+            "}")
+        .doTest(TestMode.TEXT_MATCH);
+  }
+}

error-prone-contrib/src/test/java/tech/picnic/errorprone/refasterrules/RefasterRulesTest.java

@@ -43,6 +43,7 @@ final class RefasterRulesTest {
           EqualityRules.class,
           FileRules.class,
           InputStreamRules.class,
+          ImmutableEnumSetRules.class,
           ImmutableListRules.class,
           ImmutableListMultimapRules.class,
           ImmutableMapRules.class,
@@ -58,6 +59,7 @@ final class RefasterRulesTest {
           LongStreamRules.class,
           MapEntryRules.class,
           MapRules.class,
+          MicrometerRules.class,
           MockitoRules.class,
           MultimapRules.class,
           NullRules.class,

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/AssortedRulesTestInput.java

@@ -1,10 +1,7 @@
 package tech.picnic.errorprone.refasterrules;
 
-import static com.google.common.collect.ImmutableSet.toImmutableSet;
-
 import com.google.common.base.Preconditions;
 import com.google.common.base.Splitter;
-import com.google.common.collect.BoundType;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
@@ -24,8 +21,7 @@ final class AssortedRulesTest implements RefasterRuleCollectionTestCase {
         Preconditions.class,
         Sets.class,
         Splitter.class,
-        Streams.class,
-        toImmutableSet());
+        Streams.class);
   }
 
   int testCheckIndex() {
@@ -38,10 +34,6 @@ final class AssortedRulesTest implements RefasterRuleCollectionTestCase {
     }
   }
 
-  ImmutableSet<BoundType> testStreamToImmutableEnumSet() {
-    return Stream.of(BoundType.OPEN).collect(toImmutableSet());
-  }
-
   ImmutableSet<String> testIteratorGetNextOrDefault() {
     return ImmutableSet.of(
         ImmutableList.of("a").iterator().hasNext()

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/AssortedRulesTestOutput.java

@@ -1,12 +1,9 @@
 package tech.picnic.errorprone.refasterrules;
 
-import static com.google.common.collect.ImmutableSet.toImmutableSet;
-import static com.google.common.collect.Sets.toImmutableEnumSet;
 import static java.util.Objects.checkIndex;
 
 import com.google.common.base.Preconditions;
 import com.google.common.base.Splitter;
-import com.google.common.collect.BoundType;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
@@ -27,8 +24,7 @@ final class AssortedRulesTest implements RefasterRuleCollectionTestCase {
         Preconditions.class,
         Sets.class,
         Splitter.class,
-        Streams.class,
-        toImmutableSet());
+        Streams.class);
   }
 
   int testCheckIndex() {
@@ -39,10 +35,6 @@ final class AssortedRulesTest implements RefasterRuleCollectionTestCase {
     checkIndex(1, 2);
   }
 
-  ImmutableSet<BoundType> testStreamToImmutableEnumSet() {
-    return Stream.of(BoundType.OPEN).collect(toImmutableEnumSet());
-  }
-
   ImmutableSet<String> testIteratorGetNextOrDefault() {
     return ImmutableSet.of(
         Iterators.getNext(ImmutableList.of("a").iterator(), "foo"),

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/BugCheckerRulesTestInput.java

@@ -4,13 +4,15 @@ import com.google.common.collect.ImmutableSet;
 import com.google.errorprone.BugCheckerRefactoringTestHelper;
 import com.google.errorprone.BugCheckerRefactoringTestHelper.FixChoosers;
 import com.google.errorprone.bugpatterns.BugChecker;
+import com.sun.tools.javac.util.Constants;
 import com.sun.tools.javac.util.Convert;
+import javax.lang.model.element.Name;
 import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
 
 final class BugCheckerRulesTest implements RefasterRuleCollectionTestCase {
   @Override
   public ImmutableSet<Object> elidedTypesAndStaticImports() {
-    return ImmutableSet.of(Convert.class, FixChoosers.class);
+    return ImmutableSet.of(Constants.class, Convert.class, FixChoosers.class);
   }
 
   ImmutableSet<BugCheckerRefactoringTestHelper> testBugCheckerRefactoringTestHelperIdentity() {
@@ -28,7 +30,13 @@ final class BugCheckerRulesTest implements RefasterRuleCollectionTestCase {
         .addOutputLines("A.java", "class A {}");
   }
 
-  String testConstantsFormat() {
-    return String.format("\"%s\"", Convert.quote("foo"));
+  ImmutableSet<String> testConstantsFormat() {
+    return ImmutableSet.of(Constants.format("foo"), String.format("\"%s\"", Convert.quote("bar")));
+  }
+
+  ImmutableSet<Boolean> testNameContentEquals() {
+    return ImmutableSet.of(
+        ((Name) null).toString().equals("foo".subSequence(0, 1).toString()),
+        ((com.sun.tools.javac.util.Name) null).toString().equals("bar"));
   }
 }

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/BugCheckerRulesTestOutput.java

@@ -6,12 +6,14 @@ import com.google.errorprone.BugCheckerRefactoringTestHelper.FixChoosers;
 import com.google.errorprone.bugpatterns.BugChecker;
 import com.sun.tools.javac.util.Constants;
 import com.sun.tools.javac.util.Convert;
+import javax.lang.model.element.Name;
 import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
+import tech.picnic.errorprone.utils.SourceCode;
 
 final class BugCheckerRulesTest implements RefasterRuleCollectionTestCase {
   @Override
   public ImmutableSet<Object> elidedTypesAndStaticImports() {
-    return ImmutableSet.of(Convert.class, FixChoosers.class);
+    return ImmutableSet.of(Constants.class, Convert.class, FixChoosers.class);
   }
 
   ImmutableSet<BugCheckerRefactoringTestHelper> testBugCheckerRefactoringTestHelperIdentity() {
@@ -27,7 +29,15 @@ final class BugCheckerRulesTest implements RefasterRuleCollectionTestCase {
         .expectUnchanged();
   }
 
-  String testConstantsFormat() {
-    return Constants.format("foo");
+  ImmutableSet<String> testConstantsFormat() {
+    return ImmutableSet.of(
+        SourceCode.toStringConstantExpression("foo", /* REPLACEME */ null),
+        SourceCode.toStringConstantExpression("bar", /* REPLACEME */ null));
+  }
+
+  ImmutableSet<Boolean> testNameContentEquals() {
+    return ImmutableSet.of(
+        ((Name) null).contentEquals("foo".subSequence(0, 1)),
+        ((com.sun.tools.javac.util.Name) null).contentEquals("bar"));
   }
 }

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ClassRulesTestInput.java

@@ -1,26 +1,30 @@
 package tech.picnic.errorprone.refasterrules;
 
 import com.google.common.collect.ImmutableSet;
-import java.io.IOException;
+import java.util.function.Function;
 import java.util.function.Predicate;
 import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
 
 final class ClassRulesTest implements RefasterRuleCollectionTestCase {
-  boolean testClassIsInstance() throws IOException {
+  boolean testClassIsInstance() {
     return CharSequence.class.isAssignableFrom("foo".getClass());
   }
 
-  ImmutableSet<Boolean> testInstanceof() throws IOException {
+  ImmutableSet<Boolean> testInstanceof() {
     Class<?> clazz = CharSequence.class;
     return ImmutableSet.of(CharSequence.class.isInstance("foo"), clazz.isInstance("bar"));
   }
 
-  Predicate<String> testClassLiteralIsInstancePredicate() throws IOException {
+  Predicate<String> testClassLiteralIsInstancePredicate() {
     return s -> s instanceof CharSequence;
   }
 
-  Predicate<String> testClassReferenceIsInstancePredicate() throws IOException {
+  Predicate<String> testClassReferenceIsInstancePredicate() {
     Class<?> clazz = CharSequence.class;
     return s -> clazz.isInstance(s);
   }
+
+  Function<Number, Integer> testClassReferenceCast() {
+    return i -> Integer.class.cast(i);
+  }
 }

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ClassRulesTestOutput.java

@@ -1,26 +1,30 @@
 package tech.picnic.errorprone.refasterrules;
 
 import com.google.common.collect.ImmutableSet;
-import java.io.IOException;
+import java.util.function.Function;
 import java.util.function.Predicate;
 import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
 
 final class ClassRulesTest implements RefasterRuleCollectionTestCase {
-  boolean testClassIsInstance() throws IOException {
+  boolean testClassIsInstance() {
     return CharSequence.class.isInstance("foo");
   }
 
-  ImmutableSet<Boolean> testInstanceof() throws IOException {
+  ImmutableSet<Boolean> testInstanceof() {
     Class<?> clazz = CharSequence.class;
     return ImmutableSet.of("foo" instanceof CharSequence, clazz.isInstance("bar"));
   }
 
-  Predicate<String> testClassLiteralIsInstancePredicate() throws IOException {
+  Predicate<String> testClassLiteralIsInstancePredicate() {
     return CharSequence.class::isInstance;
   }
 
-  Predicate<String> testClassReferenceIsInstancePredicate() throws IOException {
+  Predicate<String> testClassReferenceIsInstancePredicate() {
     Class<?> clazz = CharSequence.class;
     return clazz::isInstance;
   }
+
+  Function<Number, Integer> testClassReferenceCast() {
+    return Integer.class::cast;
+  }
 }

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/CollectionRulesTestInput.java

@@ -6,9 +6,11 @@ import com.google.common.collect.ImmutableSortedSet;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Lists;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.LinkedList;
+import java.util.List;
 import java.util.Optional;
 import java.util.TreeSet;
 import java.util.stream.Stream;
@@ -70,6 +72,10 @@ final class CollectionRulesTest implements RefasterRuleCollectionTestCase {
     }
   }
 
+  Stream<Integer> testSetStream() {
+    return ImmutableSet.of(1).stream().distinct();
+  }
+
   ArrayList<String> testNewArrayListFromCollection() {
     return Lists.newArrayList(ImmutableList.of("foo"));
   }
@@ -94,6 +100,10 @@ final class CollectionRulesTest implements RefasterRuleCollectionTestCase {
     return ImmutableSet.of(1).asList().toString();
   }
 
+  List<String> testArraysAsList() {
+    return Arrays.stream(new String[0]).toList();
+  }
+
   ImmutableSet<Object[]> testCollectionToArray() {
     return ImmutableSet.of(
         ImmutableSet.of(1).toArray(new Object[1]),
@@ -109,8 +119,9 @@ final class CollectionRulesTest implements RefasterRuleCollectionTestCase {
     return ImmutableSet.of(1).asList().toArray(Integer[]::new);
   }
 
-  Iterator<Integer> testImmutableCollectionIterator() {
-    return ImmutableSet.of(1).asList().iterator();
+  ImmutableSet<Iterator<Integer>> testCollectionIterator() {
+    return ImmutableSet.of(
+        ImmutableSet.of(1).stream().iterator(), ImmutableSet.of(2).asList().iterator());
   }
 
   ImmutableSet<Optional<Integer>> testOptionalFirstCollectionElement() {

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/CollectionRulesTestOutput.java

@@ -6,9 +6,11 @@ import com.google.common.collect.ImmutableSortedSet;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Lists;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.LinkedList;
+import java.util.List;
 import java.util.Optional;
 import java.util.TreeSet;
 import java.util.stream.Stream;
@@ -62,6 +64,10 @@ final class CollectionRulesTest implements RefasterRuleCollectionTestCase {
     new HashSet<Number>().removeAll(ImmutableSet.of(2));
   }
 
+  Stream<Integer> testSetStream() {
+    return ImmutableSet.of(1).stream();
+  }
+
   ArrayList<String> testNewArrayListFromCollection() {
     return new ArrayList<>(ImmutableList.of("foo"));
   }
@@ -86,6 +92,10 @@ final class CollectionRulesTest implements RefasterRuleCollectionTestCase {
     return ImmutableSet.of(1).toString();
   }
 
+  List<String> testArraysAsList() {
+    return Arrays.asList(new String[0]);
+  }
+
   ImmutableSet<Object[]> testCollectionToArray() {
     return ImmutableSet.of(
         ImmutableSet.of(1).toArray(), ImmutableSet.of(2).toArray(), ImmutableSet.of(3).toArray());
@@ -99,8 +109,8 @@ final class CollectionRulesTest implements RefasterRuleCollectionTestCase {
     return ImmutableSet.of(1).toArray(Integer[]::new);
   }
 
-  Iterator<Integer> testImmutableCollectionIterator() {
-    return ImmutableSet.of(1).iterator();
+  ImmutableSet<Iterator<Integer>> testCollectionIterator() {
+    return ImmutableSet.of(ImmutableSet.of(1).iterator(), ImmutableSet.of(2).iterator());
   }
 
   ImmutableSet<Optional<Integer>> testOptionalFirstCollectionElement() {

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ComparatorRulesTestInput.java

@@ -107,6 +107,24 @@ final class ComparatorRulesTest implements RefasterRuleCollectionTestCase {
         Comparator.<String>reverseOrder().compare("baz", "qux"));
   }
 
+  void testCollectionsSort() {
+    Collections.sort(ImmutableList.of("foo", "bar"), naturalOrder());
+  }
+
+  ImmutableSet<String> testCollectionsMin() {
+    return ImmutableSet.of(
+        Collections.min(ImmutableList.of("foo"), naturalOrder()),
+        Collections.max(ImmutableList.of("bar"), reverseOrder()));
+  }
+
+  String testMinOfArray() {
+    return Arrays.stream(new String[0]).min(naturalOrder()).orElseThrow();
+  }
+
+  String testCollectionsMinWithComparator() {
+    return ImmutableSet.of("foo", "bar").stream().min(naturalOrder()).orElseThrow();
+  }
+
   int testMinOfVarargs() {
     return Stream.of(1, 2).min(naturalOrder()).orElseThrow();
   }
@@ -135,6 +153,20 @@ final class ComparatorRulesTest implements RefasterRuleCollectionTestCase {
         Collections.min(ImmutableSet.of("a", "b"), (a, b) -> 1));
   }
 
+  ImmutableSet<String> testCollectionsMax() {
+    return ImmutableSet.of(
+        Collections.max(ImmutableList.of("foo"), naturalOrder()),
+        Collections.min(ImmutableList.of("bar"), reverseOrder()));
+  }
+
+  String testMaxOfArray() {
+    return Arrays.stream(new String[0]).max(naturalOrder()).orElseThrow();
+  }
+
+  String testCollectionsMaxWithComparator() {
+    return ImmutableSet.of("foo", "bar").stream().max(naturalOrder()).orElseThrow();
+  }
+
   int testMaxOfVarargs() {
     return Stream.of(1, 2).max(naturalOrder()).orElseThrow();
   }

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ComparatorRulesTestOutput.java

@@ -98,6 +98,23 @@ final class ComparatorRulesTest implements RefasterRuleCollectionTestCase {
     return ImmutableSet.of("foo".compareTo("bar"), "qux".compareTo("baz"));
   }
 
+  void testCollectionsSort() {
+    Collections.sort(ImmutableList.of("foo", "bar"));
+  }
+
+  ImmutableSet<String> testCollectionsMin() {
+    return ImmutableSet.of(
+        Collections.min(ImmutableList.of("foo")), Collections.min(ImmutableList.of("bar")));
+  }
+
+  String testMinOfArray() {
+    return Collections.min(Arrays.asList(new String[0]), naturalOrder());
+  }
+
+  String testCollectionsMinWithComparator() {
+    return Collections.min(ImmutableSet.of("foo", "bar"), naturalOrder());
+  }
+
   int testMinOfVarargs() {
     return Collections.min(Arrays.asList(1, 2), naturalOrder());
   }
@@ -126,6 +143,19 @@ final class ComparatorRulesTest implements RefasterRuleCollectionTestCase {
         Comparators.min("a", "b", (a, b) -> 1));
   }
 
+  ImmutableSet<String> testCollectionsMax() {
+    return ImmutableSet.of(
+        Collections.max(ImmutableList.of("foo")), Collections.max(ImmutableList.of("bar")));
+  }
+
+  String testMaxOfArray() {
+    return Collections.max(Arrays.asList(new String[0]), naturalOrder());
+  }
+
+  String testCollectionsMaxWithComparator() {
+    return Collections.max(ImmutableSet.of("foo", "bar"), naturalOrder());
+  }
+
   int testMaxOfVarargs() {
     return Collections.max(Arrays.asList(1, 2), naturalOrder());
   }

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/FileRulesTestInput.java

@@ -1,12 +1,28 @@
 package tech.picnic.errorprone.refasterrules;
 
+import com.google.common.collect.ImmutableSet;
+import java.io.File;
 import java.io.IOException;
+import java.net.URI;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
+import java.nio.file.Path;
 import java.nio.file.Paths;
 import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
 
 final class FileRulesTest implements RefasterRuleCollectionTestCase {
+  Path testPathOfUri() {
+    return Paths.get(URI.create("foo"));
+  }
+
+  ImmutableSet<Path> testPathOfString() {
+    return ImmutableSet.of(Paths.get("foo"), Paths.get("bar", "baz", "qux"));
+  }
+
+  Path testPathInstance() {
+    return Path.of("foo").toFile().toPath();
+  }
+
   String testFilesReadStringWithCharset() throws IOException {
     return new String(Files.readAllBytes(Paths.get("foo")), StandardCharsets.ISO_8859_1);
   }
@@ -14,4 +30,13 @@ final class FileRulesTest implements RefasterRuleCollectionTestCase {
   String testFilesReadString() throws IOException {
     return Files.readString(Paths.get("foo"), StandardCharsets.UTF_8);
   }
+
+  ImmutableSet<File> testFilesCreateTempFileToFile() throws IOException {
+    return ImmutableSet.of(
+        File.createTempFile("foo", "bar"), File.createTempFile("baz", "qux", null));
+  }
+
+  File testFilesCreateTempFileInCustomDirectoryToFile() throws IOException {
+    return File.createTempFile("foo", "bar", new File("baz"));
+  }
 }

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/FileRulesTestOutput.java

@@ -1,12 +1,28 @@
 package tech.picnic.errorprone.refasterrules;
 
+import com.google.common.collect.ImmutableSet;
+import java.io.File;
 import java.io.IOException;
+import java.net.URI;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
+import java.nio.file.Path;
 import java.nio.file.Paths;
 import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
 
 final class FileRulesTest implements RefasterRuleCollectionTestCase {
+  Path testPathOfUri() {
+    return Path.of(URI.create("foo"));
+  }
+
+  ImmutableSet<Path> testPathOfString() {
+    return ImmutableSet.of(Path.of("foo"), Path.of("bar", "baz", "qux"));
+  }
+
+  Path testPathInstance() {
+    return Path.of("foo");
+  }
+
   String testFilesReadStringWithCharset() throws IOException {
     return Files.readString(Paths.get("foo"), StandardCharsets.ISO_8859_1);
   }
@@ -14,4 +30,13 @@ final class FileRulesTest implements RefasterRuleCollectionTestCase {
   String testFilesReadString() throws IOException {
     return Files.readString(Paths.get("foo"));
   }
+
+  ImmutableSet<File> testFilesCreateTempFileToFile() throws IOException {
+    return ImmutableSet.of(
+        Files.createTempFile("foo", "bar").toFile(), Files.createTempFile("baz", "qux").toFile());
+  }
+
+  File testFilesCreateTempFileInCustomDirectoryToFile() throws IOException {
+    return Files.createTempFile(new File("baz").toPath(), "foo", "bar").toFile();
+  }
 }

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ImmutableEnumSetRulesTestInput.java

@@ -0,0 +1,96 @@
+package tech.picnic.errorprone.refasterrules;
+
+import static com.google.common.collect.ImmutableSet.toImmutableSet;
+
+import com.google.common.collect.BoundType;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Iterables;
+import java.math.RoundingMode;
+import java.util.EnumSet;
+import java.util.stream.Stream;
+import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
+
+final class ImmutableEnumSetRulesTest implements RefasterRuleCollectionTestCase {
+  @Override
+  public ImmutableSet<Object> elidedTypesAndStaticImports() {
+    return ImmutableSet.of(EnumSet.class, toImmutableSet());
+  }
+
+  ImmutableSet<ImmutableSet<RoundingMode>> testSetsImmutableEnumSetIterable() {
+    return ImmutableSet.of(
+        ImmutableSet.copyOf(Iterables.cycle(RoundingMode.UP)),
+        ImmutableSet.copyOf(EnumSet.allOf(RoundingMode.class)));
+  }
+
+  ImmutableSet<RoundingMode> testSetsImmutableEnumSetArraysAsList() {
+    return ImmutableSet.copyOf(RoundingMode.values());
+  }
+
+  ImmutableSet<ImmutableSet<RoundingMode>> testSetsImmutableEnumSet1() {
+    return ImmutableSet.of(
+        ImmutableSet.of(RoundingMode.UP), ImmutableSet.copyOf(EnumSet.of(RoundingMode.UP)));
+  }
+
+  ImmutableSet<ImmutableSet<RoundingMode>> testSetsImmutableEnumSet2() {
+    return ImmutableSet.of(
+        ImmutableSet.of(RoundingMode.UP, RoundingMode.DOWN),
+        ImmutableSet.copyOf(EnumSet.of(RoundingMode.UP, RoundingMode.DOWN)));
+  }
+
+  ImmutableSet<ImmutableSet<RoundingMode>> testSetsImmutableEnumSet3() {
+    return ImmutableSet.of(
+        ImmutableSet.of(RoundingMode.UP, RoundingMode.DOWN, RoundingMode.CEILING),
+        ImmutableSet.copyOf(EnumSet.of(RoundingMode.UP, RoundingMode.DOWN, RoundingMode.CEILING)));
+  }
+
+  ImmutableSet<ImmutableSet<RoundingMode>> testSetsImmutableEnumSet4() {
+    return ImmutableSet.of(
+        ImmutableSet.of(
+            RoundingMode.UP, RoundingMode.DOWN, RoundingMode.CEILING, RoundingMode.FLOOR),
+        ImmutableSet.copyOf(
+            EnumSet.of(
+                RoundingMode.UP, RoundingMode.DOWN, RoundingMode.CEILING, RoundingMode.FLOOR)));
+  }
+
+  ImmutableSet<ImmutableSet<RoundingMode>> testSetsImmutableEnumSet5() {
+    return ImmutableSet.of(
+        ImmutableSet.of(
+            RoundingMode.UP,
+            RoundingMode.DOWN,
+            RoundingMode.CEILING,
+            RoundingMode.FLOOR,
+            RoundingMode.UNNECESSARY),
+        ImmutableSet.copyOf(
+            EnumSet.of(
+                RoundingMode.UP,
+                RoundingMode.DOWN,
+                RoundingMode.CEILING,
+                RoundingMode.FLOOR,
+                RoundingMode.UNNECESSARY)));
+  }
+
+  ImmutableSet<RoundingMode> testSetsImmutableEnumSet6() {
+    return ImmutableSet.of(
+        RoundingMode.UP,
+        RoundingMode.DOWN,
+        RoundingMode.CEILING,
+        RoundingMode.FLOOR,
+        RoundingMode.UNNECESSARY,
+        RoundingMode.HALF_EVEN);
+  }
+
+  ImmutableSet<RoundingMode> testSetsImmutableEnumSetVarArgs() {
+    return ImmutableSet.copyOf(
+        EnumSet.of(
+            RoundingMode.UP,
+            RoundingMode.DOWN,
+            RoundingMode.CEILING,
+            RoundingMode.FLOOR,
+            RoundingMode.UNNECESSARY,
+            RoundingMode.HALF_EVEN));
+  }
+
+  ImmutableSet<BoundType> testStreamToImmutableEnumSet() {
+    return Stream.of(BoundType.OPEN).collect(toImmutableSet());
+  }
+}

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ImmutableEnumSetRulesTestOutput.java

@@ -0,0 +1,96 @@
+package tech.picnic.errorprone.refasterrules;
+
+import static com.google.common.collect.ImmutableSet.toImmutableSet;
+import static com.google.common.collect.Sets.toImmutableEnumSet;
+
+import com.google.common.collect.BoundType;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Iterables;
+import com.google.common.collect.Sets;
+import java.math.RoundingMode;
+import java.util.Arrays;
+import java.util.EnumSet;
+import java.util.stream.Stream;
+import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
+
+final class ImmutableEnumSetRulesTest implements RefasterRuleCollectionTestCase {
+  @Override
+  public ImmutableSet<Object> elidedTypesAndStaticImports() {
+    return ImmutableSet.of(EnumSet.class, toImmutableSet());
+  }
+
+  ImmutableSet<ImmutableSet<RoundingMode>> testSetsImmutableEnumSetIterable() {
+    return ImmutableSet.of(
+        Sets.immutableEnumSet(Iterables.cycle(RoundingMode.UP)),
+        Sets.immutableEnumSet(EnumSet.allOf(RoundingMode.class)));
+  }
+
+  ImmutableSet<RoundingMode> testSetsImmutableEnumSetArraysAsList() {
+    return Sets.immutableEnumSet(Arrays.asList(RoundingMode.values()));
+  }
+
+  ImmutableSet<ImmutableSet<RoundingMode>> testSetsImmutableEnumSet1() {
+    return ImmutableSet.of(
+        Sets.immutableEnumSet(RoundingMode.UP), Sets.immutableEnumSet(RoundingMode.UP));
+  }
+
+  ImmutableSet<ImmutableSet<RoundingMode>> testSetsImmutableEnumSet2() {
+    return ImmutableSet.of(
+        Sets.immutableEnumSet(RoundingMode.UP, RoundingMode.DOWN),
+        Sets.immutableEnumSet(RoundingMode.UP, RoundingMode.DOWN));
+  }
+
+  ImmutableSet<ImmutableSet<RoundingMode>> testSetsImmutableEnumSet3() {
+    return ImmutableSet.of(
+        Sets.immutableEnumSet(RoundingMode.UP, RoundingMode.DOWN, RoundingMode.CEILING),
+        Sets.immutableEnumSet(RoundingMode.UP, RoundingMode.DOWN, RoundingMode.CEILING));
+  }
+
+  ImmutableSet<ImmutableSet<RoundingMode>> testSetsImmutableEnumSet4() {
+    return ImmutableSet.of(
+        Sets.immutableEnumSet(
+            RoundingMode.UP, RoundingMode.DOWN, RoundingMode.CEILING, RoundingMode.FLOOR),
+        Sets.immutableEnumSet(
+            RoundingMode.UP, RoundingMode.DOWN, RoundingMode.CEILING, RoundingMode.FLOOR));
+  }
+
+  ImmutableSet<ImmutableSet<RoundingMode>> testSetsImmutableEnumSet5() {
+    return ImmutableSet.of(
+        Sets.immutableEnumSet(
+            RoundingMode.UP,
+            RoundingMode.DOWN,
+            RoundingMode.CEILING,
+            RoundingMode.FLOOR,
+            RoundingMode.UNNECESSARY),
+        Sets.immutableEnumSet(
+            RoundingMode.UP,
+            RoundingMode.DOWN,
+            RoundingMode.CEILING,
+            RoundingMode.FLOOR,
+            RoundingMode.UNNECESSARY));
+  }
+
+  ImmutableSet<RoundingMode> testSetsImmutableEnumSet6() {
+    return Sets.immutableEnumSet(
+        RoundingMode.UP,
+        RoundingMode.DOWN,
+        RoundingMode.CEILING,
+        RoundingMode.FLOOR,
+        RoundingMode.UNNECESSARY,
+        RoundingMode.HALF_EVEN);
+  }
+
+  ImmutableSet<RoundingMode> testSetsImmutableEnumSetVarArgs() {
+    return Sets.immutableEnumSet(
+        RoundingMode.UP,
+        RoundingMode.DOWN,
+        RoundingMode.CEILING,
+        RoundingMode.FLOOR,
+        RoundingMode.UNNECESSARY,
+        RoundingMode.HALF_EVEN);
+  }
+
+  ImmutableSet<BoundType> testStreamToImmutableEnumSet() {
+    return Stream.of(BoundType.OPEN).collect(toImmutableEnumSet());
+  }
+}

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ImmutableMultisetRulesTestInput.java

@@ -26,6 +26,7 @@ final class ImmutableMultisetRulesTest implements RefasterRuleCollectionTestCase
         Stream.<Integer>empty().collect(toImmutableMultiset()));
   }
 
+  @SuppressWarnings("unchecked")
   ImmutableMultiset<ImmutableMultiset<Integer>> testIterableToImmutableMultiset() {
     return ImmutableMultiset.of(
         ImmutableList.of(1).stream().collect(toImmutableMultiset()),

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ImmutableMultisetRulesTestOutput.java

@@ -24,6 +24,7 @@ final class ImmutableMultisetRulesTest implements RefasterRuleCollectionTestCase
     return ImmutableMultiset.of(ImmutableMultiset.of(), ImmutableMultiset.of());
   }
 
+  @SuppressWarnings("unchecked")
   ImmutableMultiset<ImmutableMultiset<Integer>> testIterableToImmutableMultiset() {
     return ImmutableMultiset.of(
         ImmutableMultiset.copyOf(ImmutableList.of(1)),

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ImmutableSortedMultisetRulesTestInput.java

@@ -37,6 +37,7 @@ final class ImmutableSortedMultisetRulesTest implements RefasterRuleCollectionTe
         Stream.<Integer>empty().collect(toImmutableSortedMultiset(naturalOrder())));
   }
 
+  @SuppressWarnings("unchecked")
   ImmutableMultiset<ImmutableSortedMultiset<Integer>> testIterableToImmutableSortedMultiset() {
     return ImmutableMultiset.of(
         ImmutableSortedMultiset.copyOf(naturalOrder(), ImmutableList.of(1)),

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ImmutableSortedMultisetRulesTestOutput.java

@@ -35,6 +35,7 @@ final class ImmutableSortedMultisetRulesTest implements RefasterRuleCollectionTe
     return ImmutableMultiset.of(ImmutableSortedMultiset.of(), ImmutableSortedMultiset.of());
   }
 
+  @SuppressWarnings("unchecked")
   ImmutableMultiset<ImmutableSortedMultiset<Integer>> testIterableToImmutableSortedMultiset() {
     return ImmutableMultiset.of(
         ImmutableSortedMultiset.copyOf(ImmutableList.of(1)),

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/MicrometerRulesTestInput.java

@@ -0,0 +1,57 @@
+package tech.picnic.errorprone.refasterrules;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import io.micrometer.core.instrument.Tag;
+import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
+
+final class MicrometerRulesTest implements RefasterRuleCollectionTestCase {
+  @Override
+  public ImmutableSet<Object> elidedTypesAndStaticImports() {
+    return ImmutableSet.of(ImmutableList.class);
+  }
+
+  ImmutableSet<Iterable<Tag>> testTagsOf1() {
+    return ImmutableSet.of(
+        ImmutableSet.of(Tag.of("foo", "v1")), ImmutableList.of(Tag.of("bar", "v2")));
+  }
+
+  ImmutableSet<Iterable<Tag>> testTagsOf2() {
+    return ImmutableSet.of(
+        ImmutableSet.of(Tag.of("foo", "v1"), Tag.of("bar", "v2")),
+        ImmutableList.of(Tag.of("baz", "v3"), Tag.of("qux", "v4")));
+  }
+
+  ImmutableSet<Iterable<Tag>> testTagsOf3() {
+    return ImmutableSet.of(
+        ImmutableSet.of(Tag.of("foo", "v1"), Tag.of("bar", "v2"), Tag.of("baz", "v3")),
+        ImmutableList.of(Tag.of("qux", "v4"), Tag.of("quux", "v5"), Tag.of("corge", "v6")));
+  }
+
+  ImmutableSet<Iterable<Tag>> testTagsOf4() {
+    return ImmutableSet.of(
+        ImmutableSet.of(
+            Tag.of("foo", "v1"), Tag.of("bar", "v2"), Tag.of("baz", "v3"), Tag.of("qux", "v4")),
+        ImmutableList.of(
+            Tag.of("quux", "v5"),
+            Tag.of("corge", "v6"),
+            Tag.of("grault", "v7"),
+            Tag.of("garply", "v8")));
+  }
+
+  ImmutableSet<Iterable<Tag>> testTagsOf5() {
+    return ImmutableSet.of(
+        ImmutableSet.of(
+            Tag.of("foo", "v1"),
+            Tag.of("bar", "v2"),
+            Tag.of("baz", "v3"),
+            Tag.of("qux", "v4"),
+            Tag.of("quux", "v5")),
+        ImmutableList.of(
+            Tag.of("corge", "v6"),
+            Tag.of("grault", "v7"),
+            Tag.of("garply", "v8"),
+            Tag.of("waldo", "v9"),
+            Tag.of("fred", "v10")));
+  }
+}

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/MicrometerRulesTestOutput.java

@@ -0,0 +1,56 @@
+package tech.picnic.errorprone.refasterrules;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import io.micrometer.core.instrument.Tag;
+import io.micrometer.core.instrument.Tags;
+import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
+
+final class MicrometerRulesTest implements RefasterRuleCollectionTestCase {
+  @Override
+  public ImmutableSet<Object> elidedTypesAndStaticImports() {
+    return ImmutableSet.of(ImmutableList.class);
+  }
+
+  ImmutableSet<Iterable<Tag>> testTagsOf1() {
+    return ImmutableSet.of(Tags.of(Tag.of("foo", "v1")), Tags.of(Tag.of("bar", "v2")));
+  }
+
+  ImmutableSet<Iterable<Tag>> testTagsOf2() {
+    return ImmutableSet.of(
+        Tags.of(Tag.of("foo", "v1"), Tag.of("bar", "v2")),
+        Tags.of(Tag.of("baz", "v3"), Tag.of("qux", "v4")));
+  }
+
+  ImmutableSet<Iterable<Tag>> testTagsOf3() {
+    return ImmutableSet.of(
+        Tags.of(Tag.of("foo", "v1"), Tag.of("bar", "v2"), Tag.of("baz", "v3")),
+        Tags.of(Tag.of("qux", "v4"), Tag.of("quux", "v5"), Tag.of("corge", "v6")));
+  }
+
+  ImmutableSet<Iterable<Tag>> testTagsOf4() {
+    return ImmutableSet.of(
+        Tags.of(Tag.of("foo", "v1"), Tag.of("bar", "v2"), Tag.of("baz", "v3"), Tag.of("qux", "v4")),
+        Tags.of(
+            Tag.of("quux", "v5"),
+            Tag.of("corge", "v6"),
+            Tag.of("grault", "v7"),
+            Tag.of("garply", "v8")));
+  }
+
+  ImmutableSet<Iterable<Tag>> testTagsOf5() {
+    return ImmutableSet.of(
+        Tags.of(
+            Tag.of("foo", "v1"),
+            Tag.of("bar", "v2"),
+            Tag.of("baz", "v3"),
+            Tag.of("qux", "v4"),
+            Tag.of("quux", "v5")),
+        Tags.of(
+            Tag.of("corge", "v6"),
+            Tag.of("grault", "v7"),
+            Tag.of("garply", "v8"),
+            Tag.of("waldo", "v9"),
+            Tag.of("fred", "v10")));
+  }
+}

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/OptionalRulesTestInput.java

@@ -83,11 +83,9 @@ final class OptionalRulesTest implements RefasterRuleCollectionTestCase {
     return Optional.of("foo").orElseGet(() -> Optional.of("bar").orElseThrow());
   }
 
-  ImmutableSet<String> testOptionalOrElseGet() {
+  ImmutableSet<String> testOptionalOrElse() {
     return ImmutableSet.of(
-        Optional.of("foo").orElse("bar"),
-        Optional.of("baz").orElse(toString()),
-        Optional.of("qux").orElse(String.valueOf(true)));
+        Optional.of("foo").orElseGet(() -> "bar"), Optional.of("baz").orElseGet(() -> toString()));
   }
 
   ImmutableSet<Object> testStreamFlatMapOptional() {

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/OptionalRulesTestOutput.java

@@ -80,11 +80,9 @@ final class OptionalRulesTest implements RefasterRuleCollectionTestCase {
     return Optional.of("foo").or(() -> Optional.of("bar")).orElseThrow();
   }
 
-  ImmutableSet<String> testOptionalOrElseGet() {
+  ImmutableSet<String> testOptionalOrElse() {
     return ImmutableSet.of(
-        Optional.of("foo").orElse("bar"),
-        Optional.of("baz").orElse(toString()),
-        Optional.of("qux").orElseGet(() -> String.valueOf(true)));
+        Optional.of("foo").orElse("bar"), Optional.of("baz").orElseGet(() -> toString()));
   }
 
   ImmutableSet<Object> testStreamFlatMapOptional() {

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/PrimitiveRulesTestInput.java

@@ -9,6 +9,8 @@ import com.google.common.primitives.Floats;
 import com.google.common.primitives.Ints;
 import com.google.common.primitives.Longs;
 import com.google.common.primitives.Shorts;
+import com.google.common.primitives.UnsignedInts;
+import com.google.common.primitives.UnsignedLongs;
 import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
 
 final class PrimitiveRulesTest implements RefasterRuleCollectionTestCase {
@@ -22,7 +24,9 @@ final class PrimitiveRulesTest implements RefasterRuleCollectionTestCase {
         Floats.class,
         Ints.class,
         Longs.class,
-        Shorts.class);
+        Shorts.class,
+        UnsignedInts.class,
+        UnsignedLongs.class);
   }
 
   ImmutableSet<Boolean> testLessThan() {
@@ -105,34 +109,6 @@ final class PrimitiveRulesTest implements RefasterRuleCollectionTestCase {
     return Doubles.hashCode(1);
   }
 
-  int testBooleanCompare() {
-    return Booleans.compare(false, true);
-  }
-
-  int testCharacterCompare() {
-    return Chars.compare('a', 'b');
-  }
-
-  int testShortCompare() {
-    return Shorts.compare((short) 1, (short) 2);
-  }
-
-  int testIntegerCompare() {
-    return Ints.compare(1, 2);
-  }
-
-  int testLongCompare() {
-    return Longs.compare(1, 2);
-  }
-
-  int testFloatCompare() {
-    return Floats.compare(1, 2);
-  }
-
-  int testDoubleCompare() {
-    return Doubles.compare(1, 2);
-  }
-
   int testCharacterBytes() {
     return Chars.BYTES;
   }
@@ -190,4 +166,60 @@ final class PrimitiveRulesTest implements RefasterRuleCollectionTestCase {
     return ImmutableSet.of(
         Long.signum(1L) < 0, Long.signum(2L) <= -1, Long.signum(3L) >= 0, Long.signum(4L) > -1);
   }
+
+  int testIntegerCompareUnsigned() {
+    return UnsignedInts.compare(1, 2);
+  }
+
+  long testLongCompareUnsigned() {
+    return UnsignedLongs.compare(1, 2);
+  }
+
+  int testIntegerDivideUnsigned() {
+    return UnsignedInts.divide(1, 2);
+  }
+
+  long testLongDivideUnsigned() {
+    return UnsignedLongs.divide(1, 2);
+  }
+
+  int testIntegerRemainderUnsigned() {
+    return UnsignedInts.remainder(1, 2);
+  }
+
+  long testLongRemainderUnsigned() {
+    return UnsignedLongs.remainder(1, 2);
+  }
+
+  ImmutableSet<Integer> testIntegerParseUnsignedInt() {
+    return ImmutableSet.of(UnsignedInts.parseUnsignedInt("1"), Integer.parseUnsignedInt("2", 10));
+  }
+
+  ImmutableSet<Long> testLongParseUnsignedLong() {
+    return ImmutableSet.of(UnsignedLongs.parseUnsignedLong("1"), Long.parseUnsignedLong("2", 10));
+  }
+
+  int testIntegerParseUnsignedIntWithRadix() {
+    return UnsignedInts.parseUnsignedInt("1", 2);
+  }
+
+  long testLongParseUnsignedLongWithRadix() {
+    return UnsignedLongs.parseUnsignedLong("1", 2);
+  }
+
+  ImmutableSet<String> testIntegerToUnsignedString() {
+    return ImmutableSet.of(UnsignedInts.toString(1), Integer.toUnsignedString(2, 10));
+  }
+
+  ImmutableSet<String> testLongToUnsignedString() {
+    return ImmutableSet.of(UnsignedLongs.toString(1), Long.toUnsignedString(2, 10));
+  }
+
+  String testIntegerToUnsignedStringWithRadix() {
+    return UnsignedInts.toString(1, 2);
+  }
+
+  String testLongToUnsignedStringWithRadix() {
+    return UnsignedLongs.toString(1, 2);
+  }
 }

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/PrimitiveRulesTestOutput.java

@@ -9,6 +9,8 @@ import com.google.common.primitives.Floats;
 import com.google.common.primitives.Ints;
 import com.google.common.primitives.Longs;
 import com.google.common.primitives.Shorts;
+import com.google.common.primitives.UnsignedInts;
+import com.google.common.primitives.UnsignedLongs;
 import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
 
 final class PrimitiveRulesTest implements RefasterRuleCollectionTestCase {
@@ -22,7 +24,9 @@ final class PrimitiveRulesTest implements RefasterRuleCollectionTestCase {
         Floats.class,
         Ints.class,
         Longs.class,
-        Shorts.class);
+        Shorts.class,
+        UnsignedInts.class,
+        UnsignedLongs.class);
   }
 
   ImmutableSet<Boolean> testLessThan() {
@@ -105,34 +109,6 @@ final class PrimitiveRulesTest implements RefasterRuleCollectionTestCase {
     return Double.hashCode(1);
   }
 
-  int testBooleanCompare() {
-    return Boolean.compare(false, true);
-  }
-
-  int testCharacterCompare() {
-    return Character.compare('a', 'b');
-  }
-
-  int testShortCompare() {
-    return Short.compare((short) 1, (short) 2);
-  }
-
-  int testIntegerCompare() {
-    return Integer.compare(1, 2);
-  }
-
-  int testLongCompare() {
-    return Long.compare(1, 2);
-  }
-
-  int testFloatCompare() {
-    return Float.compare(1, 2);
-  }
-
-  int testDoubleCompare() {
-    return Double.compare(1, 2);
-  }
-
   int testCharacterBytes() {
     return Character.BYTES;
   }
@@ -190,4 +166,60 @@ final class PrimitiveRulesTest implements RefasterRuleCollectionTestCase {
     return ImmutableSet.of(
         Long.signum(1L) == -1, Long.signum(2L) == -1, Long.signum(3L) != -1, Long.signum(4L) != -1);
   }
+
+  int testIntegerCompareUnsigned() {
+    return Integer.compareUnsigned(1, 2);
+  }
+
+  long testLongCompareUnsigned() {
+    return Long.compareUnsigned(1, 2);
+  }
+
+  int testIntegerDivideUnsigned() {
+    return Integer.divideUnsigned(1, 2);
+  }
+
+  long testLongDivideUnsigned() {
+    return Long.divideUnsigned(1, 2);
+  }
+
+  int testIntegerRemainderUnsigned() {
+    return Integer.remainderUnsigned(1, 2);
+  }
+
+  long testLongRemainderUnsigned() {
+    return Long.remainderUnsigned(1, 2);
+  }
+
+  ImmutableSet<Integer> testIntegerParseUnsignedInt() {
+    return ImmutableSet.of(Integer.parseUnsignedInt("1"), Integer.parseUnsignedInt("2"));
+  }
+
+  ImmutableSet<Long> testLongParseUnsignedLong() {
+    return ImmutableSet.of(Long.parseUnsignedLong("1"), Long.parseUnsignedLong("2"));
+  }
+
+  int testIntegerParseUnsignedIntWithRadix() {
+    return Integer.parseUnsignedInt("1", 2);
+  }
+
+  long testLongParseUnsignedLongWithRadix() {
+    return Long.parseUnsignedLong("1", 2);
+  }
+
+  ImmutableSet<String> testIntegerToUnsignedString() {
+    return ImmutableSet.of(Integer.toUnsignedString(1), Integer.toUnsignedString(2));
+  }
+
+  ImmutableSet<String> testLongToUnsignedString() {
+    return ImmutableSet.of(Long.toUnsignedString(1), Long.toUnsignedString(2));
+  }
+
+  String testIntegerToUnsignedStringWithRadix() {
+    return Integer.toUnsignedString(1, 2);
+  }
+
+  String testLongToUnsignedStringWithRadix() {
+    return Long.toUnsignedString(1, 2);
+  }
 }

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestInput.java

@@ -10,6 +10,7 @@ import static java.util.stream.Collectors.minBy;
 import static java.util.stream.Collectors.toCollection;
 import static org.assertj.core.api.Assertions.assertThat;
 
+import com.github.benmanes.caffeine.cache.AsyncLoadingCache;
 import com.google.common.collect.ImmutableCollection;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
@@ -23,6 +24,7 @@ import java.util.Optional;
 import java.util.concurrent.Callable;
 import java.util.concurrent.CompletableFuture;
 import java.util.function.Supplier;
+import java.util.stream.Stream;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 import reactor.math.MathFlux;
@@ -434,8 +436,10 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
         Flux.just(ImmutableList.of("bar")).concatMap(Flux::fromIterable, 2));
   }
 
-  Flux<String> testFluxFromIterable() {
-    return Flux.fromStream(ImmutableList.of("foo").stream());
+  ImmutableSet<Flux<String>> testFluxFromIterable() {
+    return ImmutableSet.of(
+        Flux.fromStream(ImmutableList.of("foo")::stream),
+        Flux.fromStream(() -> ImmutableList.of("bar").stream()));
   }
 
   ImmutableSet<Mono<Integer>> testFluxCountMapMathToIntExact() {
@@ -594,6 +598,18 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
     return StepVerifier.create(Flux.just(1));
   }
 
+  Object testStepVerifierVerify() {
+    return Mono.empty().as(StepVerifier::create).expectError().verifyThenAssertThat();
+  }
+
+  Object testStepVerifierVerifyDuration() {
+    return Mono.empty().as(StepVerifier::create).expectError().verifyThenAssertThat(Duration.ZERO);
+  }
+
+  StepVerifier testStepVerifierVerifyLater() {
+    return Mono.empty().as(StepVerifier::create).expectError().verifyLater().verifyLater();
+  }
+
   ImmutableSet<StepVerifier.Step<Integer>> testStepVerifierStepIdentity() {
     return ImmutableSet.of(
         Mono.just(1).as(StepVerifier::create).expectNext(),
@@ -634,17 +650,43 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
             .verifyErrorSatisfies(t -> assertThat(t).isInstanceOf(AssertionError.class)));
   }
 
-  Duration testStepVerifierLastStepVerifyErrorMatches() {
-    return Mono.empty()
-        .as(StepVerifier::create)
-        .expectErrorMatches(IllegalArgumentException.class::equals)
-        .verify();
+  ImmutableSet<?> testStepVerifierLastStepVerifyErrorMatches() {
+    return ImmutableSet.of(
+        Mono.empty()
+            .as(StepVerifier::create)
+            .expectErrorMatches(IllegalArgumentException.class::equals)
+            .verify(),
+        Mono.empty()
+            .as(StepVerifier::create)
+            .expectError()
+            .verifyThenAssertThat()
+            .hasOperatorErrorMatching(IllegalStateException.class::equals));
   }
 
   Duration testStepVerifierLastStepVerifyErrorSatisfies() {
     return Mono.empty().as(StepVerifier::create).expectErrorSatisfies(t -> {}).verify();
   }
 
+  ImmutableSet<?> testStepVerifierLastStepVerifyErrorSatisfiesAssertJ() {
+    return ImmutableSet.of(
+        Mono.empty()
+            .as(StepVerifier::create)
+            .expectError()
+            .verifyThenAssertThat()
+            .hasOperatorErrorOfType(IllegalArgumentException.class)
+            .hasOperatorErrorWithMessage("foo"),
+        Mono.empty()
+            .as(StepVerifier::create)
+            .expectError(IllegalStateException.class)
+            .verifyThenAssertThat()
+            .hasOperatorErrorWithMessage("bar"),
+        Mono.empty()
+            .as(StepVerifier::create)
+            .expectErrorMessage("baz")
+            .verifyThenAssertThat()
+            .hasOperatorErrorOfType(AssertionError.class));
+  }
+
   Duration testStepVerifierLastStepVerifyErrorMessage() {
     return Mono.empty().as(StepVerifier::create).expectErrorMessage("foo").verify();
   }
@@ -660,4 +702,12 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
   Mono<Void> testMonoFromFutureSupplierBoolean() {
     return Mono.fromFuture(CompletableFuture.completedFuture(null), true);
   }
+
+  Mono<String> testMonoFromFutureAsyncLoadingCacheGet() {
+    return Mono.fromFuture(() -> ((AsyncLoadingCache<Integer, String>) null).get(0));
+  }
+
+  Flux<Integer> testFluxFromStreamSupplier() {
+    return Flux.fromStream(Stream.of(1));
+  }
 }

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestOutput.java

@@ -12,6 +12,7 @@ import static java.util.stream.Collectors.toCollection;
 import static org.assertj.core.api.Assertions.assertThat;
 import static reactor.function.TupleUtils.function;
 
+import com.github.benmanes.caffeine.cache.AsyncLoadingCache;
 import com.google.common.collect.ImmutableCollection;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
@@ -25,6 +26,7 @@ import java.util.Optional;
 import java.util.concurrent.Callable;
 import java.util.concurrent.CompletableFuture;
 import java.util.function.Supplier;
+import java.util.stream.Stream;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 import reactor.function.TupleUtils;
@@ -429,8 +431,9 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
         Flux.just(ImmutableList.of("bar")).concatMapIterable(identity(), 2));
   }
 
-  Flux<String> testFluxFromIterable() {
-    return Flux.fromIterable(ImmutableList.of("foo"));
+  ImmutableSet<Flux<String>> testFluxFromIterable() {
+    return ImmutableSet.of(
+        Flux.fromIterable(ImmutableList.of("foo")), Flux.fromIterable(ImmutableList.of("bar")));
   }
 
   ImmutableSet<Mono<Integer>> testFluxCountMapMathToIntExact() {
@@ -583,6 +586,18 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
     return Flux.just(1).as(StepVerifier::create);
   }
 
+  Object testStepVerifierVerify() {
+    return Mono.empty().as(StepVerifier::create).expectError().verify();
+  }
+
+  Object testStepVerifierVerifyDuration() {
+    return Mono.empty().as(StepVerifier::create).expectError().verify(Duration.ZERO);
+  }
+
+  StepVerifier testStepVerifierVerifyLater() {
+    return Mono.empty().as(StepVerifier::create).expectError().verifyLater();
+  }
+
   ImmutableSet<StepVerifier.Step<Integer>> testStepVerifierStepIdentity() {
     return ImmutableSet.of(
         Mono.just(1).as(StepVerifier::create),
@@ -616,16 +631,36 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
         Mono.empty().as(StepVerifier::create).verifyError(AssertionError.class));
   }
 
-  Duration testStepVerifierLastStepVerifyErrorMatches() {
-    return Mono.empty()
-        .as(StepVerifier::create)
-        .verifyErrorMatches(IllegalArgumentException.class::equals);
+  ImmutableSet<?> testStepVerifierLastStepVerifyErrorMatches() {
+    return ImmutableSet.of(
+        Mono.empty()
+            .as(StepVerifier::create)
+            .verifyErrorMatches(IllegalArgumentException.class::equals),
+        Mono.empty()
+            .as(StepVerifier::create)
+            .verifyErrorMatches(IllegalStateException.class::equals));
   }
 
   Duration testStepVerifierLastStepVerifyErrorSatisfies() {
     return Mono.empty().as(StepVerifier::create).verifyErrorSatisfies(t -> {});
   }
 
+  ImmutableSet<?> testStepVerifierLastStepVerifyErrorSatisfiesAssertJ() {
+    return ImmutableSet.of(
+        Mono.empty()
+            .as(StepVerifier::create)
+            .verifyErrorSatisfies(
+                t -> assertThat(t).isInstanceOf(IllegalArgumentException.class).hasMessage("foo")),
+        Mono.empty()
+            .as(StepVerifier::create)
+            .verifyErrorSatisfies(
+                t -> assertThat(t).isInstanceOf(IllegalStateException.class).hasMessage("bar")),
+        Mono.empty()
+            .as(StepVerifier::create)
+            .verifyErrorSatisfies(
+                t -> assertThat(t).isInstanceOf(AssertionError.class).hasMessage("baz")));
+  }
+
   Duration testStepVerifierLastStepVerifyErrorMessage() {
     return Mono.empty().as(StepVerifier::create).verifyErrorMessage("foo");
   }
@@ -641,4 +676,12 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
   Mono<Void> testMonoFromFutureSupplierBoolean() {
     return Mono.fromFuture(() -> CompletableFuture.completedFuture(null), true);
   }
+
+  Mono<String> testMonoFromFutureAsyncLoadingCacheGet() {
+    return Mono.fromFuture(() -> ((AsyncLoadingCache<Integer, String>) null).get(0), true);
+  }
+
+  Flux<Integer> testFluxFromStreamSupplier() {
+    return Flux.fromStream(() -> Stream.of(1));
+  }
 }

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/StringRulesTestInput.java

@@ -96,4 +96,32 @@ final class StringRulesTest implements RefasterRuleCollectionTestCase {
   int testUtf8EncodedLength() {
     return "foo".getBytes(UTF_8).length;
   }
+
+  int testStringIndexOfChar() {
+    return "foo".substring(1).indexOf('a');
+  }
+
+  int testStringIndexOfString() {
+    return "foo".substring(1).indexOf("bar");
+  }
+
+  int testStringLastIndexOfChar() {
+    return "foo".substring(1).lastIndexOf('a');
+  }
+
+  int testStringLastIndexOfString() {
+    return "foo".substring(1).lastIndexOf("bar");
+  }
+
+  int testStringLastIndexOfCharWithIndex() {
+    return "foo".substring(0, 2).lastIndexOf('a');
+  }
+
+  int testStringLastIndexOfStringWithIndex() {
+    return "foo".substring(0, 2).lastIndexOf("bar");
+  }
+
+  boolean testStringStartsWith() {
+    return "foo".substring(1).startsWith("bar");
+  }
 }

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/StringRulesTestOutput.java

@@ -96,4 +96,32 @@ final class StringRulesTest implements RefasterRuleCollectionTestCase {
   int testUtf8EncodedLength() {
     return Utf8.encodedLength("foo");
   }
+
+  int testStringIndexOfChar() {
+    return Math.max(-1, "foo".indexOf('a', 1) - 1);
+  }
+
+  int testStringIndexOfString() {
+    return Math.max(-1, "foo".indexOf("bar", 1) - 1);
+  }
+
+  int testStringLastIndexOfChar() {
+    return Math.max(-1, "foo".lastIndexOf('a') - 1);
+  }
+
+  int testStringLastIndexOfString() {
+    return Math.max(-1, "foo".lastIndexOf("bar") - 1);
+  }
+
+  int testStringLastIndexOfCharWithIndex() {
+    return "foo".lastIndexOf('a', 2 - 1);
+  }
+
+  int testStringLastIndexOfStringWithIndex() {
+    return "foo".lastIndexOf("bar", 2 - 1);
+  }
+
+  boolean testStringStartsWith() {
+    return "foo".startsWith("bar", 1);
+  }
 }

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/TimeRulesTestInput.java

@@ -66,6 +66,32 @@ final class TimeRulesTest implements RefasterRuleCollectionTestCase {
     return Instant.EPOCH.atZone(ZoneOffset.UTC).toOffsetDateTime();
   }
 
+  ImmutableSet<Instant> testInstantIdentity() {
+    return ImmutableSet.of(
+        Instant.EPOCH.plusMillis(1).plus(Duration.ZERO),
+        Instant.EPOCH.plusMillis(2).plus(0, ChronoUnit.MILLIS),
+        Instant.EPOCH.plusMillis(3).plusNanos(0L),
+        Instant.EPOCH.plusMillis(4).plusMillis(0),
+        Instant.EPOCH.plusMillis(5).plusSeconds(0L),
+        Instant.EPOCH.plusMillis(6).minus(Duration.ZERO),
+        Instant.EPOCH.plusMillis(7).minus(0, ChronoUnit.SECONDS),
+        Instant.EPOCH.plusMillis(8).minusNanos(0L),
+        Instant.EPOCH.plusMillis(9).minusMillis(0),
+        Instant.EPOCH.plusMillis(10).minusSeconds(0L),
+        Instant.parse(Instant.EPOCH.plusMillis(11).toString()),
+        Instant.EPOCH.plusMillis(12).truncatedTo(ChronoUnit.NANOS),
+        Instant.ofEpochSecond(
+            Instant.EPOCH.plusMillis(13).getEpochSecond(), Instant.EPOCH.plusMillis(13).getNano()));
+  }
+
+  Instant testInstantTruncatedToMilliseconds() {
+    return Instant.ofEpochMilli(Instant.EPOCH.toEpochMilli());
+  }
+
+  Instant testInstantTruncatedToSeconds() {
+    return Instant.ofEpochSecond(Instant.EPOCH.getEpochSecond());
+  }
+
   OffsetDateTime testInstantAtOffset() {
     return OffsetDateTime.ofInstant(Instant.EPOCH, ZoneOffset.UTC);
   }

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/TimeRulesTestOutput.java

@@ -66,6 +66,31 @@ final class TimeRulesTest implements RefasterRuleCollectionTestCase {
     return OffsetDateTime.ofInstant(Instant.EPOCH, ZoneOffset.UTC);
   }
 
+  ImmutableSet<Instant> testInstantIdentity() {
+    return ImmutableSet.of(
+        Instant.EPOCH.plusMillis(1),
+        Instant.EPOCH.plusMillis(2),
+        Instant.EPOCH.plusMillis(3),
+        Instant.EPOCH.plusMillis(4),
+        Instant.EPOCH.plusMillis(5),
+        Instant.EPOCH.plusMillis(6),
+        Instant.EPOCH.plusMillis(7),
+        Instant.EPOCH.plusMillis(8),
+        Instant.EPOCH.plusMillis(9),
+        Instant.EPOCH.plusMillis(10),
+        Instant.EPOCH.plusMillis(11),
+        Instant.EPOCH.plusMillis(12),
+        Instant.EPOCH.plusMillis(13));
+  }
+
+  Instant testInstantTruncatedToMilliseconds() {
+    return Instant.EPOCH.truncatedTo(ChronoUnit.MILLIS);
+  }
+
+  Instant testInstantTruncatedToSeconds() {
+    return Instant.EPOCH.truncatedTo(ChronoUnit.SECONDS);
+  }
+
   OffsetDateTime testInstantAtOffset() {
     return Instant.EPOCH.atOffset(ZoneOffset.UTC);
   }

error-prone-experimental/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.17.0</version>
+        <version>0.19.2-SNAPSHOT</version>
     </parent>
 
     <artifactId>error-prone-experimental</artifactId>

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

@@ -73,19 +73,18 @@ public final class MethodReferenceUsage extends BugChecker implements LambdaExpr
      * because the latter are not syntactically valid or ambiguous. Rather than encoding all these
      * edge cases we try to compile the code with the suggested fix, to see whether this works.
      */
-    return constructMethodRef(tree, tree.getBody())
-        .map(SuggestedFix.Builder::build)
-        .filter(
-            fix ->
-                SuggestedFixes.compilesWithFix(
-                    fix, state, ImmutableList.of(), /* onlyInSameCompilationUnit= */ true))
-        .map(fix -> describeMatch(tree, fix))
-        .orElse(Description.NO_MATCH);
+    SuggestedFix fix = constructMethodRef(tree, tree.getBody());
+    if (fix.isEmpty()
+        || !SuggestedFixes.compilesWithFix(
+            fix, state, ImmutableList.of(), /* onlyInSameCompilationUnit= */ true)) {
+      return Description.NO_MATCH;
+    }
+
+    return describeMatch(tree, fix);
   }
 
   // XXX: Use switch pattern matching once the targeted JDK supports this.
-  private static Optional<SuggestedFix.Builder> constructMethodRef(
-      LambdaExpressionTree lambdaExpr, Tree subTree) {
+  private static SuggestedFix constructMethodRef(LambdaExpressionTree lambdaExpr, Tree subTree) {
     return switch (subTree.getKind()) {
       case BLOCK -> constructMethodRef(lambdaExpr, (BlockTree) subTree);
       case EXPRESSION_STATEMENT ->
@@ -94,27 +93,28 @@ public final class MethodReferenceUsage extends BugChecker implements LambdaExpr
       case PARENTHESIZED ->
           constructMethodRef(lambdaExpr, ((ParenthesizedTree) subTree).getExpression());
       case RETURN -> constructMethodRef(lambdaExpr, ((ReturnTree) subTree).getExpression());
-      default -> Optional.empty();
+      default -> SuggestedFix.emptyFix();
     };
   }
 
-  private static Optional<SuggestedFix.Builder> constructMethodRef(
+  private static SuggestedFix constructMethodRef(
       LambdaExpressionTree lambdaExpr, BlockTree subTree) {
     return Optional.of(subTree.getStatements())
         .filter(statements -> statements.size() == 1)
-        .flatMap(statements -> constructMethodRef(lambdaExpr, statements.get(0)));
+        .map(statements -> constructMethodRef(lambdaExpr, statements.get(0)))
+        .orElseGet(SuggestedFix::emptyFix);
   }
 
-  // XXX: Replace nested `Optional` usage.
   @SuppressWarnings("NestedOptionals")
-  private static Optional<SuggestedFix.Builder> constructMethodRef(
+  private static SuggestedFix constructMethodRef(
       LambdaExpressionTree lambdaExpr, MethodInvocationTree subTree) {
     return matchArguments(lambdaExpr, subTree)
-        .flatMap(expectedInstance -> constructMethodRef(lambdaExpr, subTree, expectedInstance));
+        .map(expectedInstance -> constructMethodRef(lambdaExpr, subTree, expectedInstance))
+        .orElseGet(SuggestedFix::emptyFix);
   }
 
   // XXX: Review whether to use switch pattern matching once the targeted JDK supports this.
-  private static Optional<SuggestedFix.Builder> constructMethodRef(
+  private static SuggestedFix constructMethodRef(
       LambdaExpressionTree lambdaExpr,
       MethodInvocationTree subTree,
       Optional<Name> expectedInstance) {
@@ -123,7 +123,7 @@ public final class MethodReferenceUsage extends BugChecker implements LambdaExpr
     if (methodSelect instanceof IdentifierTree) {
       if (expectedInstance.isPresent()) {
         /* Direct method call; there is no matching "implicit parameter". */
-        return Optional.empty();
+        return SuggestedFix.emptyFix();
       }
 
       Symbol sym = ASTHelpers.getSymbol(methodSelect);
@@ -139,7 +139,7 @@ public final class MethodReferenceUsage extends BugChecker implements LambdaExpr
     throw new VerifyException("Unexpected type of expression: " + methodSelect.getKind());
   }
 
-  private static Optional<SuggestedFix.Builder> constructMethodRef(
+  private static SuggestedFix constructMethodRef(
       LambdaExpressionTree lambdaExpr, MemberSelectTree subTree, Optional<Name> expectedInstance) {
     if (!(subTree.getExpression() instanceof IdentifierTree identifier)) {
       // XXX: Could be parenthesized. Handle. Also in other classes.
@@ -147,7 +147,7 @@ public final class MethodReferenceUsage extends BugChecker implements LambdaExpr
        * Only suggest a replacement if the method select's expression provably doesn't have
        * side-effects. Otherwise the replacement may not be behavior preserving.
        */
-      return Optional.empty();
+      return SuggestedFix.emptyFix();
     }
 
     Name lhs = identifier.getName();
@@ -157,7 +157,7 @@ public final class MethodReferenceUsage extends BugChecker implements LambdaExpr
 
     Type lhsType = ASTHelpers.getType(identifier);
     if (lhsType == null || !expectedInstance.orElseThrow().equals(lhs)) {
-      return Optional.empty();
+      return SuggestedFix.emptyFix();
     }
 
     // XXX: Dropping generic type information is in most cases fine or even more likely to yield a
@@ -195,23 +195,23 @@ public final class MethodReferenceUsage extends BugChecker implements LambdaExpr
 
   // XXX: Resolve this suppression.
   @SuppressWarnings("UnqualifiedSuggestedFixImport")
-  private static Optional<SuggestedFix.Builder> constructFix(
+  private static SuggestedFix constructFix(
       LambdaExpressionTree lambdaExpr, Symbol target, Object methodName) {
     Name sName = target.getSimpleName();
-    Optional<SuggestedFix.Builder> fix = constructFix(lambdaExpr, sName, methodName);
+    SuggestedFix fix = constructFix(lambdaExpr, sName, methodName);
 
     if (!"java.lang".equals(ASTHelpers.enclosingPackage(target).toString())) {
       Name fqName = target.getQualifiedName();
       if (!sName.equals(fqName)) {
-        return fix.map(b -> b.addImport(fqName.toString()));
+        return fix.toBuilder().addImport(fqName.toString()).build();
       }
     }
 
     return fix;
   }
 
-  private static Optional<SuggestedFix.Builder> constructFix(
+  private static SuggestedFix constructFix(
       LambdaExpressionTree lambdaExpr, Object target, Object methodName) {
-    return Optional.of(SuggestedFix.builder().replace(lambdaExpr, target + "::" + methodName));
+    return SuggestedFix.replace(lambdaExpr, target + "::" + methodName);
   }
 }

error-prone-guidelines/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.17.0</version>
+        <version>0.19.2-SNAPSHOT</version>
     </parent>
 
     <artifactId>error-prone-guidelines</artifactId>

error-prone-guidelines/src/main/java/tech/picnic/errorprone/guidelines/bugpatterns/BugPatternLink.java

@@ -30,8 +30,8 @@ import com.sun.source.tree.BinaryTree;
 import com.sun.source.tree.ClassTree;
 import com.sun.source.tree.ExpressionTree;
 import com.sun.source.tree.Tree.Kind;
-import com.sun.tools.javac.util.Constants;
 import javax.lang.model.element.Name;
+import tech.picnic.errorprone.utils.SourceCode;
 
 /**
  * A {@link BugChecker} that flags {@link BugChecker} declarations inside {@code
@@ -126,7 +126,9 @@ public final class BugPatternLink extends BugChecker implements ClassTreeMatcher
             state,
             "link",
             ImmutableList.of(
-                linkPrefix + " + " + Constants.format(tree.getSimpleName().toString()))));
+                linkPrefix
+                    + " + "
+                    + SourceCode.toStringConstantExpression(tree.getSimpleName(), state))));
 
     String linkType =
         SuggestedFixes.qualifyStaticImport(

error-prone-guidelines/src/main/java/tech/picnic/errorprone/guidelines/bugpatterns/ErrorProneRuntimeClasspath.java

@@ -26,8 +26,8 @@ import com.sun.source.tree.LiteralTree;
 import com.sun.source.tree.MethodInvocationTree;
 import com.sun.tools.javac.code.Symbol;
 import com.sun.tools.javac.code.Symbol.ClassSymbol;
-import com.sun.tools.javac.util.Constants;
 import java.util.regex.Pattern;
+import tech.picnic.errorprone.utils.SourceCode;
 import tech.picnic.errorprone.utils.ThirdPartyLibrary;
 
 /**
@@ -123,7 +123,8 @@ public final class ErrorProneRuntimeClasspath extends BugChecker
         .setMessage("This type may not be on the runtime classpath; use a string literal instead")
         .addFix(
             SuggestedFix.replace(
-                tree, Constants.format(receiver.owner.getQualifiedName().toString())))
+                tree,
+                SourceCode.toStringConstantExpression(receiver.owner.getQualifiedName(), state)))
         .build();
   }
 
@@ -150,7 +151,9 @@ public final class ErrorProneRuntimeClasspath extends BugChecker
             original,
             identifier
                 + ".class.getCanonicalName()"
-                + (suffix.isEmpty() ? "" : (" + " + Constants.format(suffix))))
+                + (suffix.isEmpty()
+                    ? ""
+                    : (" + " + SourceCode.toStringConstantExpression(suffix, state))))
         .build();
   }
 

error-prone-guidelines/src/main/java/tech/picnic/errorprone/guidelines/bugpatterns/ExhaustiveRefasterTypeMigration.java

@@ -38,7 +38,6 @@ import com.sun.tools.javac.code.Attribute;
 import com.sun.tools.javac.code.Symbol.ClassSymbol;
 import com.sun.tools.javac.code.Symbol.MethodSymbol;
 import com.sun.tools.javac.code.Symbol.TypeSymbol;
-import com.sun.tools.javac.util.Constants;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
@@ -49,6 +48,7 @@ import javax.lang.model.element.AnnotationMirror;
 import javax.lang.model.element.AnnotationValue;
 import javax.lang.model.element.Modifier;
 import org.jspecify.annotations.Nullable;
+import tech.picnic.errorprone.utils.SourceCode;
 
 /**
  * A {@link BugChecker} that validates the claim made by {@link
@@ -129,7 +129,9 @@ public final class ExhaustiveRefasterTypeMigration extends BugChecker implements
                 migrationAnnotation,
                 state,
                 TYPE_MIGRATION_UNMIGRATED_METHODS_ELEMENT,
-                unmigratedMethods.stream().map(Constants::format).collect(toImmutableList()))
+                unmigratedMethods.stream()
+                    .map(m -> SourceCode.toStringConstantExpression(m, state))
+                    .collect(toImmutableList()))
             .build());
   }
 

error-prone-guidelines/src/main/java/tech/picnic/errorprone/guidelines/bugpatterns/RefasterMethodParameterOrder.java

@@ -35,7 +35,6 @@ import java.util.HashSet;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
-import java.util.stream.Stream;
 import javax.lang.model.element.Name;
 import org.jspecify.annotations.Nullable;
 import tech.picnic.errorprone.utils.SourceCode;
@@ -74,12 +73,11 @@ public final class RefasterMethodParameterOrder extends BugChecker implements Cl
 
     Comparator<VariableTree> canonicalOrder = determineCanonicalParameterOrder(methods);
 
-    return methods.stream()
-        .flatMap(m -> tryReorderParameters(m, canonicalOrder, state))
-        .reduce(SuggestedFix.Builder::merge)
-        .map(SuggestedFix.Builder::build)
-        .map(fix -> describeMatch(tree, fix))
-        .orElse(Description.NO_MATCH);
+    SuggestedFix fix =
+        methods.stream()
+            .map(m -> tryReorderParameters(m, canonicalOrder, state))
+            .collect(SuggestedFix.mergeFixes());
+    return fix.isEmpty() ? Description.NO_MATCH : describeMatch(tree, fix);
   }
 
   private static ImmutableList<MethodTree> getMethodsByPriority(
@@ -123,17 +121,18 @@ public final class RefasterMethodParameterOrder extends BugChecker implements Cl
     }.scan(method, null);
   }
 
-  private static Stream<SuggestedFix.Builder> tryReorderParameters(
+  private static SuggestedFix tryReorderParameters(
       MethodTree method, Comparator<VariableTree> canonicalOrder, VisitorState state) {
     List<? extends VariableTree> originalOrder = method.getParameters();
     ImmutableList<? extends VariableTree> orderedParams =
         ImmutableList.sortedCopyOf(canonicalOrder, originalOrder);
 
     return originalOrder.equals(orderedParams)
-        ? Stream.empty()
+        ? SuggestedFix.emptyFix()
         : Streams.zip(
-            originalOrder.stream(),
-            orderedParams.stream().map(p -> SourceCode.treeToString(p, state)),
-            SuggestedFix.builder()::replace);
+                originalOrder.stream(),
+                orderedParams.stream().map(p -> SourceCode.treeToString(p, state)),
+                SuggestedFix::replace)
+            .collect(SuggestedFix.mergeFixes());
   }
 }

error-prone-utils/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.17.0</version>
+        <version>0.19.2-SNAPSHOT</version>
     </parent>
 
     <artifactId>error-prone-utils</artifactId>

error-prone-utils/src/main/java/tech/picnic/errorprone/utils/Flags.java

@@ -1,6 +1,7 @@
 package tech.picnic.errorprone.utils;
 
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
 import com.google.errorprone.ErrorProneFlags;
 
 /** Helper methods for working with {@link ErrorProneFlags}. */
@@ -19,4 +20,19 @@ public final class Flags {
     ImmutableList<String> list = errorProneFlags.getListOrEmpty(name);
     return list.equals(ImmutableList.of("")) ? ImmutableList.of() : list;
   }
+
+  /**
+   * Returns the set of (comma-separated) arguments passed using the given Error Prone flag.
+   *
+   * @param errorProneFlags The full set of flags provided.
+   * @param name The name of the flag of interest.
+   * @return A non-{@code null} set of provided arguments; this set is empty if the flag was not
+   *     provided, or if the flag's value is the empty string.
+   * @implNote This method does not delegate to {@link ErrorProneFlags#getSetOrEmpty(String)}, as
+   *     that method wouldn't allow us to identify a non-singleton set of empty strings; such a set
+   *     should not be treated as empty.
+   */
+  public static ImmutableSet<String> getSet(ErrorProneFlags errorProneFlags, String name) {
+    return ImmutableSet.copyOf(getList(errorProneFlags, name));
+  }
 }