This is a squash commit of the following previous commits:

Merge branch 'master' into website

---

Undo Refaster test package split, glue it together

---

Introduce `RefasterRuleTestExtractor` for documentation generation

This new `Extractor` implementation collects Refaster example input and
output code from rule collection tests.

This change also introduces explicit compilation steps for the test
code. As a side-effect this produces faster feedback in case of invalid
input or output code.

(cherry picked from commit c8c51078332388055746b433318148f428239c18)

---

Try fix build

---

Post-rebase fix

---

Publish Error Prone compatibility matrix on website

The new `website/generate-version-compatibility-overview.sh` script
tests all combinations, and stores the result in a Jekyll data file.

---

Some cleanup

---

Make tests more maintainable

---

Try to fix htmlproofer

---

Fix source links

---

Introduce `BugPatternTestExtractor` with tests

---

Simplify tests

---

Further simplify testing setup

---

Kill another mutant and drop unused imports

---

This actually kills the mutant

---

Suggestions

---

Suggestions

---

Suggestions

---

Fix JDK 11 compatibility

---

PSM-1717 Pass `ClassLoader` to `ServiceLoader`

---

Introduce documentation generation

This is a squash commit of the following previous commits:

---

Introduce `documentation-support` module to extract website data from source code

By adding a compilation `TaskListener` that extracts data from the Bug pattern
and Refaster rule collection (test) classes and writing to JSON output files
in the target directory. This extraction happens as part of the Maven build
using the `docgen` profile.

---

Improve website styling

Co-authored-by: japborst <japborst@gmail.com>
Co-authored-by: Gijs de Jong <berichtaangijs@gmail.com>

---

Generate Markdown files from existing content for the website

---

Upgrade dependencies to the latest versions

---

Compile and install project jars before docgen

---

Run validation in build and exclude self-url

---

Reintroduce `htmlproofer`, improve templates, cleanup setup and dependencies

---

Delete directory if it exists

---

Add SCSS for GitHub button and fix bug pattern sample rendering

---

Fix bug pattern GitHub link

---

Small styling tweaks (incl. for dark theme)

---

Use single mvn command

---

Move mustache templates

---

Hardcode anchors for headings

---

Add supression to bugpatterns

---

Remove self ignore for html-proofer

---

Add refaster supressions and use callouts

---

Use v0.4.1-SNAPSHOT

---

Revert "Use single mvn command"

This reverts commit 594471d1ed23a1c19d7fe88d925d1b7f828716cd.

---

Extract Refaster samples from source code instead of AST

---

Skip verification, for now

---

Add notes on disabling bugpatterns

---

Set default layout and image

---

Fix mobile navigation

---

Revert "Set default layout and image"

This reverts commit 67a4aa7b5b4d14c0f2b783f345f53affe6ef3ec5.

---

Add supression for refaster rules

---

Post-rebase fixes

---

Fix the tests

---

Doh

---

Version bump

---

Exclude ThirdPartyLibraryTest from Bug Pattern test output

---

Remove only last occurence of 'Test' in Bug Pattern tests doc generation

---

Move `MapRulesTest` resources

---

Add exclusion for docgen of `SourceCodeTest`

---

Bump version

---

Extra fixes after rebase

---

Delete custom nav footer and `assets/images/favicon.ico`

---

Post rebase fixes with version bump to `0.8.1-SNAPSHOT`

---

Use new BugPatternTest extraction method

---

Fit Refaster extractors into new documentation support setup

---

Drop Docgen Maven profile

---

Move new rule collection

---

Improve extractor matching and update README

---

Move `SuggestedFixRules` test files

---

Fix Refaster exclusion regexes

---

Disable external link checking until the `website` branch is up-to-date with `master` again

---

Post-rebase fix

---

Not sure why `-Dverification.skip` fails while `-Dverification.warn` doesn't; won't investigate right now

---

Check external links again

---

Upgrade dependencies

---

WIP: towards dropping Mustache

---

WIP: Java doc generator

---

WIP: switch over

---

WIP: Cleanup

---

Polish

---

Bump dependencies

---

Bump Ruby

---

Sync more

---

Fix bug checker GitHub URLs

---

Fix HTMLProofer config

.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. `17.0.8`).
-- Error Prone version (e.g. `2.18.0`).
-- Error Prone Support version (e.g. `0.9.0`).
+- 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/release.yml

@@ -3,16 +3,16 @@ changelog:
     labels:
       - "ignore-changelog"
   categories:
+    - title: ":warning: Update considerations and deprecations"
+      labels:
+        - "breaking change"
+        - "deprecation"
     - title: ":rocket: New Error Prone checks and Refaster rules"
       labels:
         - "new feature"
     - title: ":sparkles: Improvements"
       labels:
         - "improvement"
-    - title: ":warning: Update considerations and deprecations"
-      labels:
-        - "breaking change"
-        - "deprecation"
     - title: ":bug: Bug fixes"
       labels:
         - "bug"

.github/workflows/build.yml

@@ -9,44 +9,55 @@ jobs:
   build:
     strategy:
       matrix:
-        os: [ ubuntu-22.04 ]
-        jdk: [ 11.0.20, 17.0.8, 21.0.0 ]
+        os: [ ubuntu-24.04 ]
+        jdk: [ 17.0.13, 21.0.5, 23.0.1 ]
         distribution: [ temurin ]
         experimental: [ false ]
         include:
-          - os: macos-12
-            jdk: 17.0.8
+          - os: macos-15
+            jdk: 17.0.13
             distribution: temurin
             experimental: false
-          - os: windows-2022
-            jdk: 17.0.8
+          - os: windows-2025
+            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@4d991eb9b905ef189e4c376166672c3f2f230481 # v2.11.0
+        with:
+          disable-sudo: true
+          egress-policy: block
+          allowed-endpoints: >
+            api.adoptium.net:443
+            github.com:443
+            github-registry-files.githubusercontent.com:443
+            jitpack.io:443
+            maven.pkg.github.com:443
+            objects.githubusercontent.com:443
+            repo.maven.apache.org:443
       # We run the build twice for each supported JDK: once against the
       # original Error Prone release, using only Error Prone checks available
       # on Maven Central, and once against the Picnic Error Prone fork,
       # additionally enabling all checks defined in this project and any Error
       # Prone checks available only from other artifact repositories.
-      - name: Check out code
-        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
-        with:
-          persist-credentials: false
-      - name: Set up JDK
-        uses: actions/setup-java@387ac29b308b003ca37ba93a6cab5eb57c8f5f93 # v4.0.0
+      - name: Check out code and set up JDK and Maven
+        uses: s4u/setup-maven-action@4f7fb9d9675e899ca81c6161dadbba0189a4ebb1 # v1.18.0
         with:
           java-version: ${{ matrix.jdk }}
-          distribution: ${{ matrix.distribution }}
-          cache: maven
+          java-distribution: ${{ matrix.distribution }}
+          maven-version: 3.9.9
       - name: Display build environment details
         run: mvn --version
       - name: Build project against vanilla Error Prone, compile Javadoc
         run: mvn -T1C install javadoc:jar
       - 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
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
       - name: Remove installed project artifacts
-        run: mvn build-helper:remove-project-artifact
+        run: mvn dependency:purge-local-repository -DmanualInclude='${project.groupId}' -DresolutionFuzziness=groupId
 
 # XXX: Enable Codecov once we "go public".

.github/workflows/codeql.yml

@@ -19,26 +19,34 @@ jobs:
     permissions:
       contents: read
       security-events: write
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
     steps:
-      - name: Check out code
-        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+      - name: Install Harden-Runner
+        uses: step-security/harden-runner@4d991eb9b905ef189e4c376166672c3f2f230481 # v2.11.0
         with:
-          persist-credentials: false
-      - name: Set up JDK
-        uses: actions/setup-java@387ac29b308b003ca37ba93a6cab5eb57c8f5f93 # v4.0.0
+          disable-sudo: true
+          egress-policy: block
+          allowed-endpoints: >
+            api.adoptium.net:443
+            api.github.com:443
+            github.com:443
+            objects.githubusercontent.com:443
+            repo.maven.apache.org:443
+            uploads.github.com:443
+      - name: Check out code and set up JDK and Maven
+        uses: s4u/setup-maven-action@4f7fb9d9675e899ca81c6161dadbba0189a4ebb1 # v1.18.0
         with:
-          java-version: 17.0.8
-          distribution: temurin
-          cache: maven
+          java-version: 17.0.13
+          java-distribution: temurin
+          maven-version: 3.9.9
       - name: Initialize CodeQL
-        uses: github/codeql-action/init@407ffafae6a767df3e0230c3df91b6443ae8df75 # v2.22.8
+        uses: github/codeql-action/init@5f8171a638ada777af81d42b55959a643bb29017 # v3.28.12
         with:
           languages: ${{ matrix.language }}
       - name: Perform minimal build
         if: matrix.language == 'java'
         run: mvn -T1C clean package -DskipTests -Dverification.skip
       - name: Perform CodeQL analysis
-        uses: github/codeql-action/analyze@407ffafae6a767df3e0230c3df91b6443ae8df75 # v2.22.8
+        uses: github/codeql-action/analyze@5f8171a638ada777af81d42b55959a643bb29017 # v3.28.12
         with:
           category: /language:${{ matrix.language }}

.github/workflows/deploy-website.yml

@@ -9,30 +9,62 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
 jobs:
   build:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
     steps:
-      - name: Check out code
-        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+      - name: Install Harden-Runner
+        uses: step-security/harden-runner@4d991eb9b905ef189e4c376166672c3f2f230481 # v2.11.0
         with:
-          persist-credentials: false
-      - uses: ruby/setup-ruby@8575951200e472d5f2d95c625da0c7bec8217c42 # v1.161.0
+          disable-sudo: true
+          egress-policy: block
+          allowed-endpoints: >
+            api.adoptium.net:443
+            api.github.com:443
+            bestpractices.coreinfrastructure.org:443
+            blog.picnic.nl:443
+            docs.github.com:443
+            errorprone.info:443
+            github.com:443
+            img.shields.io:443
+            index.rubygems.org:443
+            jitpack.io:443
+            maven.apache.org:443
+            objects.githubusercontent.com:443
+            pitest.org:443
+            repo.maven.apache.org:443
+            rubygems.org:443
+            search.maven.org:443
+            securityscorecards.dev:443
+            sonarcloud.io:443
+            www.baeldung.com:443
+            www.bestpractices.dev:443
+            www.youtube.com:443
+            youtrack.jetbrains.com:443
+      - name: Check out code and set up JDK and Maven
+        uses: s4u/setup-maven-action@4f7fb9d9675e899ca81c6161dadbba0189a4ebb1 # v1.18.0
+        with:
+          java-version: 17.0.13
+          java-distribution: temurin
+          maven-version: 3.9.9
+      - uses: ruby/setup-ruby@1a615958ad9d422dd932dc1d5823942ee002799f # v1.227.0
         with:
           working-directory: ./website
           bundler-cache: true
       - name: Configure Github Pages
-        uses: actions/configure-pages@1f0c5cde4bc74cd7e1254d0cb4de8d49e9068c7d # v4.0.0
+        uses: actions/configure-pages@983d7736d9b0ae728b81ab479565c72886d7745b # v5.0.0
+      - name: Compile project and extract data
+        run: mvn -T1C clean install -DskipTests -Dverification.skip
       - name: Generate documentation
-        run: ./generate-docs.sh
+        run: mvn exec:java@generate-docs -pl documentation-support
       - name: Build website with Jekyll
         working-directory: ./website
         run: bundle exec jekyll build
       - name: Validate HTML output
         working-directory: ./website
-        # XXX: Drop `--disable_external true` once we fully adopted the
-        # "Refaster rules" terminology on our website and in the code.
-        run: bundle exec htmlproofer --disable_external true --check-external-hash false ./_site
+        # XXX: Bealdung and StackOverflow return HTTP 403 responses when run on
+        # a GitHub Action node.
+        run: bundle exec htmlproofer --no-check-external-hash --swap-url 'https\://error-prone.picnic.tech:' --ignore-urls '/^https:\/\/(www\.baeldung\.com|stackoverflow\.com)\/.*/' ./_site
       - name: Upload website as artifact
-        uses: actions/upload-pages-artifact@a753861a5debcf57bf8b404356158c8e1e33150c # v2.0.0
+        uses: actions/upload-pages-artifact@56afc609e74202658d3ffba0e8f6dda462b719fa # v3.0.1
         with:
           path: ./website/_site
   deploy:
@@ -41,11 +73,18 @@ 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@4d991eb9b905ef189e4c376166672c3f2f230481 # v2.11.0
+        with:
+          disable-sudo: true
+          egress-policy: block
+          allowed-endpoints: >
+            api.github.com:443
       - name: Deploy to GitHub Pages
         id: deployment
-        uses: actions/deploy-pages@13b55b33dd8996121833dbc1db458c793a334630 # v3.0.1
+        uses: actions/deploy-pages@d6db90164ac5ed86f2b6aed7e0febac5b3c0c03e # v4.0.5

.github/workflows/openssf-scorecard.yml

@@ -18,19 +18,36 @@ 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@4d991eb9b905ef189e4c376166672c3f2f230481 # v2.11.0
+        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
+            github.com:443
+            index.docker.io:443
+            oss-fuzz-build-logs.storage.googleapis.com:443
+            repo.maven.apache.org:443
+            *.sigstore.dev:443
+            www.bestpractices.dev:443
       - name: Check out code
-        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           persist-credentials: false
       - name: Run OpenSSF Scorecard analysis
-        uses: ossf/scorecard-action@0864cf19026789058feabb7e87baa5f140aac736 # v2.3.1
+        uses: ossf/scorecard-action@f49aabe0b5af0936a0987cfb85d86b75731b0186 # v2.4.1
         with:
           results_file: results.sarif
           results_format: sarif
           publish_results: ${{ github.ref == 'refs/heads/master' }}
       - name: Update GitHub's code scanning dashboard
-        uses: github/codeql-action/upload-sarif@407ffafae6a767df3e0230c3df91b6443ae8df75 # v2.22.8
+        uses: github/codeql-action/upload-sarif@5f8171a638ada777af81d42b55959a643bb29017 # v3.28.12
         with:
           sarif_file: results.sarif

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

@@ -9,19 +9,25 @@ permissions:
   contents: read
 jobs:
   analyze-pr:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
     steps:
-      - name: Check out code
-        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+      - name: Install Harden-Runner
+        uses: step-security/harden-runner@4d991eb9b905ef189e4c376166672c3f2f230481 # v2.11.0
         with:
-          fetch-depth: 2
-          persist-credentials: false
-      - name: Set up JDK
-        uses: actions/setup-java@387ac29b308b003ca37ba93a6cab5eb57c8f5f93 # v4.0.0
+          disable-sudo: true
+          egress-policy: block
+          allowed-endpoints: >
+            api.adoptium.net:443
+            github.com:443
+            objects.githubusercontent.com:443
+            repo.maven.apache.org:443
+      - name: Check out code and set up JDK and Maven
+        uses: s4u/setup-maven-action@4f7fb9d9675e899ca81c6161dadbba0189a4ebb1 # v1.18.0
         with:
-          java-version: 17.0.8
-          distribution: temurin
-          cache: maven
+          checkout-fetch-depth: 2
+          java-version: 17.0.13
+          java-distribution: temurin
+          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
@@ -32,7 +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@c7d193f32edcb7bfad88892161225aeda64e9392 # v4.0.0
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
           name: pitest-reports
           path: ./target/pit-reports-ci

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

@@ -17,20 +17,27 @@ jobs:
       checks: write
       contents: read
       pull-requests: write
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
     steps:
-      - name: Check out code
-        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+      - name: Install Harden-Runner
+        uses: step-security/harden-runner@4d991eb9b905ef189e4c376166672c3f2f230481 # v2.11.0
         with:
-          persist-credentials: false
-      - name: Set up JDK
-        uses: actions/setup-java@387ac29b308b003ca37ba93a6cab5eb57c8f5f93 # v4.0.0
+          disable-sudo: true
+          egress-policy: block
+          allowed-endpoints: >
+            api.adoptium.net:443
+            api.github.com:443
+            github.com:443
+            objects.githubusercontent.com:443
+            repo.maven.apache.org:443
+      - name: Check out code and set up JDK and Maven
+        uses: s4u/setup-maven-action@4f7fb9d9675e899ca81c6161dadbba0189a4ebb1 # v1.18.0
         with:
-          java-version: 17.0.8
-          distribution: temurin
-          cache: maven
+          java-version: 17.0.13
+          java-distribution: temurin
+          maven-version: 3.9.9
       - name: Download Pitest analysis artifact
-        uses: dawidd6/action-download-artifact@e7466d1a7587ed14867642c2ca74b5bcc1e19a2d # v3.0.0
+        uses: dawidd6/action-download-artifact@09f2f74827fd3a8607589e5ad7f9398816f540fe # v3.1.4
         with:
           workflow: ${{ github.event.workflow_run.workflow_id }}
           name: pitest-reports

.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:
@@ -16,28 +16,48 @@ 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", "prometheus-java-client" ]
     steps:
-      - name: Check out code
-        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+      - name: Install Harden-Runner
+        uses: step-security/harden-runner@4d991eb9b905ef189e4c376166672c3f2f230481 # v2.11.0
         with:
-          persist-credentials: false
-          ref: refs/pull/${{ github.event.issue.number }}/head
-      - name: Set up JDK
-        uses: actions/setup-java@387ac29b308b003ca37ba93a6cab5eb57c8f5f93 # v4.0.0
+          disable-sudo: true
+          egress-policy: block
+          # XXX: After updating the validation build flags in
+          # `integration-tests/prometheus-java-client.sh`, review whether the
+          # Docker domains specified here can be dropped.
+          allowed-endpoints: >
+            api.adoptium.net:443
+            auth.docker.io:443
+            checkstyle.org:443
+            example.com:80
+            github.com:443
+            objects.githubusercontent.com:443
+            oss.sonatype.org:443
+            production.cloudflare.docker.com:443
+            raw.githubusercontent.com:443
+            registry-1.docker.io:443
+            repo.maven.apache.org:443
+            repository.sonatype.org:443
+      - name: Check out code and set up JDK and Maven
+        uses: s4u/setup-maven-action@4f7fb9d9675e899ca81c6161dadbba0189a4ebb1 # v1.18.0
         with:
-          java-version: 17.0.8
-          distribution: temurin
-          cache: maven
+          checkout-ref: "refs/pull/${{ github.event.issue.number }}/head"
+          java-version: 17.0.13
+          java-distribution: temurin
+          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-10.12.4.sh "${{ runner.temp }}/artifacts"
+        run: xvfb-run "./integration-tests/${{ matrix.integration-test }}.sh" "${{ runner.temp }}/artifacts"
       - name: Upload artifacts on failure
         if: ${{ failure() }}
-        uses: actions/upload-artifact@c7d193f32edcb7bfad88892161225aeda64e9392 # v4.0.0
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
-          name: integration-test-checkstyle-10.12.4
+          name: "integration-test-${{ 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

@@ -11,21 +11,36 @@ permissions:
   contents: read
 jobs:
   analyze:
+    # Analysis of code in forked repositories is skipped, as such workflow runs
+    # do not have access to the requisite secrets.
+    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: Check out code
-        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+      - name: Install Harden-Runner
+        uses: step-security/harden-runner@4d991eb9b905ef189e4c376166672c3f2f230481 # v2.11.0
         with:
-          fetch-depth: 0
-          persist-credentials: false
-      - name: Set up JDK
-        uses: actions/setup-java@387ac29b308b003ca37ba93a6cab5eb57c8f5f93 # v4.0.0
+          disable-sudo: true
+          egress-policy: block
+          allowed-endpoints: >
+            analysis-sensorcache-eu-central-1-prod.s3.amazonaws.com:443
+            api.adoptium.net: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
+            *.sonarcloud.io:443
+            sonarcloud.io:443
+      - name: Check out code and set up JDK and Maven
+        uses: s4u/setup-maven-action@4f7fb9d9675e899ca81c6161dadbba0189a4ebb1 # v1.18.0
         with:
-          java-version: 17.0.8
-          distribution: temurin
-          cache: maven
+          checkout-fetch-depth: 0
+          java-version: 17.0.13
+          java-distribution: temurin
+          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

.gitignore

@@ -4,6 +4,7 @@
 .DS_Store
 .factorypath
 .idea
+!.idea/icon.svg
 .project
 .settings
 target

.idea/icon.svg

@@ -0,0 +1,65 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<svg width="100%" height="100%" viewBox="0 0 1259 1199" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" xml:space="preserve" xmlns:serif="http://www.serif.com/" style="fill-rule:evenodd;clip-rule:evenodd;stroke-linejoin:round;stroke-miterlimit:2;">
+    <g transform="matrix(1,0,0,1,-624.154,-988.431)">
+        <g transform="matrix(1,0,0,1,-70.1122,-35.0561)">
+            <g transform="matrix(1,0,0,1,0,9.81959)">
+                <path d="M1227.03,1988.79C1237.78,2070.45 1225.83,2190.1 1192.24,2194.53C1158.65,2198.95 1116.14,2086.46 1105.39,2004.81C1094.64,1923.16 1128.44,1902.11 1153.32,1898.84C1178.18,1895.56 1216.28,1907.14 1227.03,1988.79Z" style="fill:rgb(219,220,211);fill-rule:nonzero;"/>
+            </g>
+            <g transform="matrix(1,0,0,1,0,9.81959)">
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+            </g>
+            <g transform="matrix(1,0,0,1,0,9.81959)">
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+            </g>
+            <g transform="matrix(1,0,0,1,0,9.81959)">
+                <path d="M1256.81,1448.61C1256.81,1472.48 1269.56,1494.57 1290.24,1506.51C1310.92,1518.45 1336.42,1518.45 1357.1,1506.51C1377.78,1494.57 1390.53,1472.48 1390.53,1448.61L1376.83,1448.61C1376.83,1467.61 1366.71,1485.15 1350.25,1494.65C1333.79,1504.15 1313.55,1504.15 1297.09,1494.65C1280.63,1485.15 1270.51,1467.61 1270.51,1448.61L1256.81,1448.61Z" style="fill:rgb(26,26,26);fill-rule:nonzero;"/>
+            </g>
+        </g>
+    </g>
+</svg>

.renovaterc.json

@@ -3,16 +3,30 @@
   "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
     },
     {
-      "matchDepNames": [
+      "matchPackageNames": [
+        "dawidd6/action-download-artifact",
         "github/codeql-action",
         "ruby/setup-ruby"
       ],

LICENSE.md

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2017-2023 Picnic Technologies BV
+Copyright (c) 2017-2024 Picnic Technologies BV
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

README.md

@@ -49,7 +49,9 @@ high-quality and consistent Java code_][picnic-blog-ep-post].
 ### Installation
 
 This library is built on top of [Error Prone][error-prone-orig-repo]. To use
-it, read the installation guide for Maven or Gradle below.
+it, read the installation guide for Maven or Gradle below. The library requires
+that your build is executed using JDK 17 or above, but supports builds that
+[target][baeldung-java-source-target-options] older versions of Java.
 
 #### Maven
 
@@ -65,6 +67,8 @@ it, read the installation guide for Maven or Gradle below.
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-compiler-plugin</artifactId>
+                   <!-- Prefer using the latest release. -->
+                   <version>3.12.0</version>
                    <configuration>
                        <annotationProcessorPaths>
                            <!-- Error Prone itself. -->
@@ -94,8 +98,6 @@ it, read the installation guide for Maven or Gradle below.
                            </arg>
                            <arg>-XDcompilePolicy=simple</arg>
                        </compilerArgs>
-                       <!-- Some checks raise warnings rather than errors. -->
-                       <showWarnings>true</showWarnings>
                        <!-- Enable this if you'd like to fail your build upon warnings. -->
                        <!-- <failOnWarning>true</failOnWarning> -->
                    </configuration>
@@ -203,19 +205,20 @@ Relevant Maven build parameters:
   version of Error Prone. This is useful e.g. when testing a locally built
   Error Prone SNAPSHOT.
 - `-Perror-prone-fork` runs the build using Picnic's [Error Prone
-  fork][error-prone-fork-repo], hosted on [Jitpack][error-prone-fork-jitpack].
-  This fork generally contains a few changes on top of the latest Error Prone
-  release.
+  fork][error-prone-fork-repo], hosted using [GitHub
+  Packages][error-prone-fork-packages]. This fork generally contains a few
+  changes on top of the latest Error Prone release. Using this profile
+  generally requires passing `-s settings.xml`, with [suitably
+  configured][github-packages-auth] `GITHUB_ACTOR` and `GITHUB_TOKEN`
+  environment variables.
 - `-Pself-check` runs the checks defined by this project against itself.
-  Pending a release of [google/error-prone#3301][error-prone-pull-3301], this
-  flag must currently be used in combination with `-Perror-prone-fork`.
 
 Other highly relevant commands:
 
 - `mvn fmt:format` formats the code using
   [`google-java-format`][google-java-format].
 - [`./run-full-build.sh`][script-run-full-build] builds the project twice,
-  where the second pass validates compatbility with Picnic's [Error Prone
+  where the second pass validates compatibility with Picnic's [Error Prone
   fork][error-prone-fork-repo] and compliance of the code with any rules
   defined within this project. (Consider running this before [opening a pull
   request][contributing-pull-request], as the PR checks also perform this
@@ -233,8 +236,9 @@ Other highly relevant commands:
   against _all_ code in the current working directory. For more information
   check the [PIT Maven plugin][pitest-maven].
 
-When running the project's tests in IntelliJ IDEA, you might see the following
-error:
+Opening the project in IntelliJ IDEA may require running `mvn clean install`
+first. Additionally, when running the project's tests using the IDE, you might
+see the following error:
 
 ```
 java: exporting a package from system module jdk.compiler is not allowed with --release
@@ -263,6 +267,7 @@ guidelines][contributing].
 If you want to report a security vulnerability, please do so through a private
 channel; please see our [security policy][security] for details.
 
+[baeldung-java-source-target-options]: https://www.baeldung.com/java-source-target-options
 [bug-checks]: https://github.com/PicnicSupermarket/error-prone-support/blob/master/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/
 [bug-checks-identity-conversion]: https://github.com/PicnicSupermarket/error-prone-support/blob/master/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/IdentityConversion.java
 [codeql-badge]: https://github.com/PicnicSupermarket/error-prone-support/actions/workflows/codeql.yml/badge.svg?branch=master&event=push
@@ -271,14 +276,14 @@ channel; please see our [security policy][security] for details.
 [contributing]: https://github.com/PicnicSupermarket/error-prone-support/blob/master/CONTRIBUTING.md
 [contributing-pull-request]: https://github.com/PicnicSupermarket/error-prone-support/blob/master/CONTRIBUTING.md#-opening-a-pull-request
 [error-prone-bugchecker]: https://github.com/google/error-prone/blob/master/check_api/src/main/java/com/google/errorprone/bugpatterns/BugChecker.java
-[error-prone-fork-jitpack]: https://jitpack.io/#PicnicSupermarket/error-prone
+[error-prone-fork-packages]: https://github.com/PicnicSupermarket/error-prone/packages
 [error-prone-fork-repo]: https://github.com/PicnicSupermarket/error-prone
 [error-prone-gradle-installation-guide]: https://github.com/tbroyer/gradle-errorprone-plugin
 [error-prone-installation-guide]: https://errorprone.info/docs/installation#maven
 [error-prone-orig-repo]: https://github.com/google/error-prone
-[error-prone-pull-3301]: https://github.com/google/error-prone/pull/3301
 [github-actions-build-badge]: https://github.com/PicnicSupermarket/error-prone-support/actions/workflows/build.yml/badge.svg
 [github-actions-build-master]: https://github.com/PicnicSupermarket/error-prone-support/actions/workflows/build.yml?query=branch:master&event=push
+[github-packages-auth]: https://docs.github.com/en/packages/working-with-a-github-packages-registry/working-with-the-apache-maven-registry#authenticating-to-github-packages
 [google-java-format]: https://github.com/google/google-java-format
 [idea-288052]: https://youtrack.jetbrains.com/issue/IDEA-288052
 [license-badge]: https://img.shields.io/github/license/PicnicSupermarket/error-prone-support
@@ -299,7 +304,7 @@ 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

@@ -5,41 +5,49 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.14.1-SNAPSHOT</version>
+        <version>0.21.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>documentation-support</artifactId>
 
     <name>Picnic :: Error Prone Support :: Documentation Support</name>
     <description>Data extraction support for the purpose of documentation generation.</description>
+    <url>https://error-prone.picnic.tech</url>
 
     <dependencies>
         <dependency>
-            <groupId>${groupId.error-prone}</groupId>
-            <artifactId>error_prone_annotation</artifactId>
+            <groupId>${project.groupId}</groupId>
+            <artifactId>error-prone-utils</artifactId>
         </dependency>
         <dependency>
-            <groupId>${groupId.error-prone}</groupId>
-            <artifactId>error_prone_annotations</artifactId>
-            <scope>provided</scope>
-        </dependency>
-        <dependency>
-            <groupId>${groupId.error-prone}</groupId>
-            <artifactId>error_prone_check_api</artifactId>
-        </dependency>
-        <dependency>
-            <groupId>${groupId.error-prone}</groupId>
-            <artifactId>error_prone_test_helpers</artifactId>
+            <groupId>${project.groupId}</groupId>
+            <artifactId>refaster-test-support</artifactId>
             <scope>test</scope>
         </dependency>
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-annotations</artifactId>
         </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-core</artifactId>
+        </dependency>
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-databind</artifactId>
         </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.dataformat</groupId>
+            <artifactId>jackson-dataformat-yaml</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.datatype</groupId>
+            <artifactId>jackson-datatype-guava</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.module</groupId>
+            <artifactId>jackson-module-parameter-names</artifactId>
+        </dependency>
         <dependency>
             <groupId>com.google.auto</groupId>
             <artifactId>auto-common</artifactId>
@@ -54,10 +62,32 @@
             <artifactId>auto-value-annotations</artifactId>
             <scope>provided</scope>
         </dependency>
+        <dependency>
+            <groupId>com.google.errorprone</groupId>
+            <artifactId>error_prone_annotation</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.google.errorprone</groupId>
+            <artifactId>error_prone_annotations</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.errorprone</groupId>
+            <artifactId>error_prone_check_api</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.google.errorprone</groupId>
+            <artifactId>error_prone_test_helpers</artifactId>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>com.google.guava</groupId>
             <artifactId>guava</artifactId>
         </dependency>
+        <dependency>
+            <groupId>io.github.java-diff-utils</groupId>
+            <artifactId>java-diff-utils</artifactId>
+        </dependency>
         <dependency>
             <groupId>org.assertj</groupId>
             <artifactId>assertj-core</artifactId>
@@ -73,6 +103,8 @@
             <artifactId>junit-jupiter-api</artifactId>
             <scope>test</scope>
         </dependency>
+        <!-- XXX: Explicitly declared as a workaround for
+        https://github.com/pitest/pitest-junit5-plugin/issues/105. -->
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-engine</artifactId>
@@ -84,4 +116,29 @@
             <scope>test</scope>
         </dependency>
     </dependencies>
+
+    <build>
+        <pluginManagement>
+            <plugins>
+                <plugin>
+                    <groupId>org.codehaus.mojo</groupId>
+                    <artifactId>exec-maven-plugin</artifactId>
+                    <executions>
+                        <execution>
+                            <id>generate-docs</id>
+                            <goals>
+                                <goal>java</goal>
+                            </goals>
+                            <configuration>
+                                <mainClass>tech.picnic.errorprone.documentation.JekyllCollectionGenerator</mainClass>
+                                <arguments>
+                                    <argument>${maven.multiModuleProjectDirectory}</argument>
+                                </arguments>
+                            </configuration>
+                        </execution>
+                    </executions>
+                </plugin>
+            </plugins>
+        </pluginManagement>
+    </build>
 </project>

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

@@ -4,6 +4,7 @@ import static com.google.common.base.Verify.verify;
 import static com.google.common.collect.ImmutableList.toImmutableList;
 import static java.util.Objects.requireNonNull;
 
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
 import com.google.auto.common.AnnotationMirrors;
 import com.google.auto.service.AutoService;
 import com.google.auto.value.AutoValue;
@@ -17,6 +18,7 @@ import com.sun.source.tree.AnnotationTree;
 import com.sun.source.tree.ClassTree;
 import com.sun.tools.javac.code.Attribute;
 import com.sun.tools.javac.code.Symbol.ClassSymbol;
+import java.net.URI;
 import java.util.Optional;
 import javax.lang.model.element.AnnotationValue;
 import tech.picnic.errorprone.documentation.BugPatternExtractor.BugPatternDocumentation;
@@ -45,7 +47,8 @@ public final class BugPatternExtractor implements Extractor<BugPatternDocumentat
     }
 
     return Optional.of(
-        new AutoValue_BugPatternExtractor_BugPatternDocumentation(
+        BugPatternDocumentation.create(
+            state.getPath().getCompilationUnit().getSourceFile().toUri(),
             symbol.getQualifiedName().toString(),
             annotation.name().isEmpty() ? tree.getSimpleName().toString() : annotation.name(),
             ImmutableList.copyOf(annotation.altNames()),
@@ -91,7 +94,36 @@ public final class BugPatternExtractor implements Extractor<BugPatternDocumentat
   }
 
   @AutoValue
+  @JsonDeserialize(as = AutoValue_BugPatternExtractor_BugPatternDocumentation.class)
   abstract static class BugPatternDocumentation {
+    static BugPatternDocumentation create(
+        URI source,
+        String fullyQualifiedName,
+        String name,
+        ImmutableList<String> altNames,
+        String link,
+        ImmutableList<String> tags,
+        String summary,
+        String explanation,
+        SeverityLevel severityLevel,
+        boolean canDisable,
+        ImmutableList<String> suppressionAnnotations) {
+      return new AutoValue_BugPatternExtractor_BugPatternDocumentation(
+          source,
+          fullyQualifiedName,
+          name,
+          altNames,
+          link,
+          tags,
+          summary,
+          explanation,
+          severityLevel,
+          canDisable,
+          suppressionAnnotations);
+    }
+
+    abstract URI source();
+
     abstract String fullyQualifiedName();
 
     abstract String name();

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

@@ -4,6 +4,13 @@ import static com.google.errorprone.matchers.Matchers.instanceMethod;
 import static com.google.errorprone.matchers.method.MethodMatchers.staticMethod;
 import static java.util.function.Predicate.not;
 
+import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.annotation.JsonPropertyOrder;
+import com.fasterxml.jackson.annotation.JsonSubTypes;
+import com.fasterxml.jackson.annotation.JsonTypeInfo;
+import com.fasterxml.jackson.annotation.JsonTypeInfo.As;
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
 import com.google.auto.service.AutoService;
 import com.google.auto.value.AutoValue;
 import com.google.common.collect.ImmutableList;
@@ -15,11 +22,12 @@ import com.sun.source.tree.ClassTree;
 import com.sun.source.tree.ExpressionTree;
 import com.sun.source.tree.MethodInvocationTree;
 import com.sun.source.util.TreeScanner;
+import java.net.URI;
 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
@@ -32,7 +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() {}
 
@@ -42,7 +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);
@@ -51,8 +59,10 @@ public final class BugPatternTestExtractor implements Extractor<TestCases> {
         .filter(not(ImmutableList::isEmpty))
         .map(
             tests ->
-                new AutoValue_BugPatternTestExtractor_TestCases(
-                    ASTHelpers.getSymbol(tree).className(), tests));
+                new AutoValue_BugPatternTestExtractor_BugPatternTestCases(
+                    state.getPath().getCompilationUnit().getSourceFile().toUri(),
+                    ASTHelpers.getSymbol(tree).className(),
+                    tests));
   }
 
   private static final class BugPatternTestCollector
@@ -67,7 +77,7 @@ public final class BugPatternTestExtractor implements Extractor<TestCases> {
                 "com.google.errorprone.CompilationTestHelper",
                 "com.google.errorprone.BugCheckerRefactoringTestHelper")
             .named("newInstance")
-            .withParameters("java.lang.Class", "java.lang.Class");
+            .withParameters(Class.class.getCanonicalName(), Class.class.getCanonicalName());
     private static final Matcher<ExpressionTree> IDENTIFICATION_SOURCE_LINES =
         instanceMethod()
             .onDescendantOf("com.google.errorprone.CompilationTestHelper")
@@ -85,10 +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
@@ -100,14 +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()));
                   }
                 });
@@ -125,12 +135,12 @@ public final class BugPatternTestExtractor implements Extractor<TestCases> {
       }
 
       ExpressionTree receiver = ASTHelpers.getReceiver(tree);
-      return receiver instanceof MethodInvocationTree
-          ? getClassUnderTest((MethodInvocationTree) receiver, state)
+      return receiver instanceof MethodInvocationTree methodInvocation
+          ? getClassUnderTest(methodInvocation, state)
           : 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);
@@ -144,12 +154,12 @@ public final class BugPatternTestExtractor implements Extractor<TestCases> {
       }
 
       ExpressionTree receiver = ASTHelpers.getReceiver(tree);
-      if (receiver instanceof MethodInvocationTree) {
-        extractIdentificationTestCases((MethodInvocationTree) receiver, sink, state);
+      if (receiver instanceof MethodInvocationTree methodInvocation) {
+        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)) {
         /*
@@ -174,8 +184,8 @@ public final class BugPatternTestExtractor implements Extractor<TestCases> {
       }
 
       ExpressionTree receiver = ASTHelpers.getReceiver(tree);
-      if (receiver instanceof MethodInvocationTree) {
-        extractReplacementTestCases((MethodInvocationTree) receiver, sink, state);
+      if (receiver instanceof MethodInvocationTree methodInvocation) {
+        extractReplacementBugPatternTestCases(methodInvocation, sink, state);
       }
     }
 
@@ -198,32 +208,80 @@ public final class BugPatternTestExtractor implements Extractor<TestCases> {
   }
 
   @AutoValue
-  abstract static class 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
-  abstract static class TestCase {
+  @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();
 
     abstract ImmutableList<TestEntry> entries();
   }
 
+  @JsonSubTypes({
+    @JsonSubTypes.Type(AutoValue_BugPatternTestExtractor_IdentificationTestEntry.class),
+    @JsonSubTypes.Type(AutoValue_BugPatternTestExtractor_ReplacementTestEntry.class)
+  })
+  @JsonTypeInfo(include = As.EXISTING_PROPERTY, property = "type", use = JsonTypeInfo.Id.DEDUCTION)
+  @JsonIgnoreProperties(ignoreUnknown = true)
+  @JsonPropertyOrder("type")
   interface TestEntry {
+    TestType type();
+
     String path();
-  }
 
-  @AutoValue
-  abstract static class ReplacementTestEntry implements TestEntry {
-    abstract String input();
-
-    abstract String output();
+    enum TestType {
+      IDENTIFICATION,
+      REPLACEMENT
+    }
   }
 
   @AutoValue
   abstract static class IdentificationTestEntry implements TestEntry {
+    static IdentificationTestEntry create(String path, String code) {
+      return new AutoValue_BugPatternTestExtractor_IdentificationTestEntry(path, code);
+    }
+
+    @JsonProperty
+    @Override
+    public final TestType type() {
+      return TestType.IDENTIFICATION;
+    }
+
     abstract String code();
   }
+
+  @AutoValue
+  abstract static class ReplacementTestEntry implements TestEntry {
+    static ReplacementTestEntry create(String path, String input, String output) {
+      return new AutoValue_BugPatternTestExtractor_ReplacementTestEntry(path, input, output);
+    }
+
+    @JsonProperty
+    @Override
+    public final TestType type() {
+      return TestType.REPLACEMENT;
+    }
+
+    abstract String input();
+
+    abstract String output();
+  }
 }

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

@@ -1,10 +1,5 @@
 package tech.picnic.errorprone.documentation;
 
-import static java.nio.charset.StandardCharsets.UTF_8;
-
-import com.fasterxml.jackson.annotation.JsonAutoDetect.Visibility;
-import com.fasterxml.jackson.annotation.PropertyAccessor;
-import com.fasterxml.jackson.databind.ObjectMapper;
 import com.google.common.collect.ImmutableList;
 import com.google.errorprone.VisitorState;
 import com.sun.source.tree.ClassTree;
@@ -15,14 +10,10 @@ import com.sun.source.util.TaskListener;
 import com.sun.source.util.TreePath;
 import com.sun.tools.javac.api.JavacTrees;
 import com.sun.tools.javac.util.Context;
-import java.io.File;
-import java.io.FileWriter;
 import java.io.IOException;
-import java.io.UncheckedIOException;
 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;
 
@@ -39,9 +30,6 @@ final class DocumentationGeneratorTaskListener implements TaskListener {
               ServiceLoader.load(
                   Extractor.class, DocumentationGeneratorTaskListener.class.getClassLoader()));
 
-  private static final ObjectMapper OBJECT_MAPPER =
-      new ObjectMapper().setVisibility(PropertyAccessor.FIELD, Visibility.ANY);
-
   private final Context context;
   private final Path docsPath;
 
@@ -94,16 +82,10 @@ final class DocumentationGeneratorTaskListener implements TaskListener {
   }
 
   private <T> void writeToFile(String identifier, String className, T data) {
-    File file = docsPath.resolve(String.format("%s-%s.json", identifier, className)).toFile();
-
-    try (FileWriter fileWriter = new FileWriter(file, UTF_8)) {
-      OBJECT_MAPPER.writeValue(fileWriter, data);
-    } catch (IOException e) {
-      throw new UncheckedIOException(String.format("Cannot write to file '%s'", file.getPath()), e);
-    }
+    Json.write(docsPath.resolve(String.format("%s-%s.json", identifier, className)), data);
   }
 
   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/JekyllCollectionGenerator.java

@@ -0,0 +1,332 @@
+package tech.picnic.errorprone.documentation;
+
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.collect.ImmutableList.toImmutableList;
+import static com.google.common.collect.ImmutableListMultimap.flatteningToImmutableListMultimap;
+import static com.google.common.collect.ImmutableMap.toImmutableMap;
+import static com.google.common.collect.ImmutableTable.toImmutableTable;
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static java.nio.charset.StandardCharsets.UTF_8;
+import static java.util.Objects.requireNonNull;
+import static java.util.stream.Collectors.joining;
+
+import com.fasterxml.jackson.annotation.JsonAutoDetect.Visibility;
+import com.fasterxml.jackson.annotation.PropertyAccessor;
+import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.dataformat.yaml.YAMLGenerator;
+import com.fasterxml.jackson.dataformat.yaml.YAMLMapper;
+import com.github.difflib.DiffUtils;
+import com.github.difflib.UnifiedDiffUtils;
+import com.github.difflib.patch.Patch;
+import com.google.auto.value.AutoValue;
+import com.google.common.base.Function;
+import com.google.common.base.Splitter;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableListMultimap;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableTable;
+import com.google.common.collect.Sets;
+import com.google.errorprone.BugPattern.SeverityLevel;
+import java.io.BufferedWriter;
+import java.io.IOException;
+import java.nio.file.FileSystems;
+import java.nio.file.FileVisitResult;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.PathMatcher;
+import java.nio.file.SimpleFileVisitor;
+import java.nio.file.attribute.BasicFileAttributes;
+import java.util.ArrayList;
+import java.util.List;
+import org.jspecify.annotations.Nullable;
+import tech.picnic.errorprone.documentation.BugPatternExtractor.BugPatternDocumentation;
+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.TestEntry;
+import tech.picnic.errorprone.documentation.RefasterRuleCollectionTestExtractor.RefasterTestCase;
+import tech.picnic.errorprone.documentation.RefasterRuleCollectionTestExtractor.RefasterTestCases;
+
+/**
+ * A command line utility that produces configuration files for the Jekyll-based Error Prone Support
+ * website.
+ */
+// XXX: Expand the class documentation.
+// XXX: Rename this class. Then also update the reference in `website/.gitignore`.
+// XXX: Now that we have bug checkers in multiple Maven modules, we should
+// likely document the source of each check on the website, perhaps even
+// grouping them by module.
+public final class JekyllCollectionGenerator {
+  // XXX: Find a bette name. Also, externalize this.
+  private static final PathMatcher PATH_MATCHER =
+      FileSystems.getDefault().getPathMatcher("glob:**/target/docs/*.json");
+
+  // XXX: Review class setup.
+  private JekyllCollectionGenerator() {}
+
+  /**
+   * Runs the application.
+   *
+   * @param args Arguments to the application; must specify the path to the Error Prone Support
+   *     project root, and nothing else.
+   * @throws IOException If any file could not be read or written.
+   */
+  public static void main(String[] args) throws IOException {
+    checkArgument(args.length == 1, "Precisely one project root path must be provided");
+    Path projectRoot = Path.of(args[0]).toAbsolutePath();
+
+    generateIndex(projectRoot);
+    PageGenerator.apply(projectRoot);
+  }
+
+  private static void generateIndex(Path projectRoot) throws IOException {
+    try (BufferedWriter writer =
+        Files.newBufferedWriter(projectRoot.resolve("website").resolve("index.md"), UTF_8)) {
+      writer.write("---");
+      writer.newLine();
+      writer.write("layout: default");
+      writer.newLine();
+      writer.write("title: Home");
+      writer.newLine();
+      writer.write("nav_order: 1");
+      writer.newLine();
+      writer.write("---");
+      writer.newLine();
+      writer.write(
+          Files.readString(projectRoot.resolve("README.md")).replace("=\"website/", "=\""));
+    }
+  }
+
+  // XXX: Review this class should be split in two: one for bug patterns and one for Refaster rules.
+  private static final class PageGenerator extends SimpleFileVisitor<Path> {
+    private static final Splitter LINE_SPLITTER = Splitter.on(System.lineSeparator());
+    private static final YAMLMapper YAML_MAPPER =
+        YAMLMapper.builder()
+            .visibility(PropertyAccessor.FIELD, Visibility.ANY)
+            .disable(JsonGenerator.Feature.AUTO_CLOSE_TARGET)
+            .enable(YAMLGenerator.Feature.MINIMIZE_QUOTES)
+            .enable(YAMLGenerator.Feature.USE_PLATFORM_LINE_BREAKS)
+            .build();
+
+    private final List<BugPatternDocumentation> bugPatterns = new ArrayList<>();
+    private final List<BugPatternTestCases> bugPatternTests = new ArrayList<>();
+    private final List<RefasterTestCases> refasterRuleCollectionTests = new ArrayList<>();
+
+    static void apply(Path projectRoot) throws IOException {
+      PageGenerator pageGenerator = new PageGenerator();
+      Files.walkFileTree(projectRoot, pageGenerator);
+      pageGenerator.writePages(projectRoot);
+    }
+
+    @Override
+    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
+      if (!PATH_MATCHER.matches(file)) {
+        return FileVisitResult.CONTINUE;
+      }
+
+      // XXX: If we use a consistent ID separator, then this can become a switch statement. Now we
+      // depend on evaluation order.
+      // XXX: Alternatively, use polymorphism and let Jackson figure it out.
+      // XXX: If we stick with an ID-based approach, then deduplicate the ID references here and in
+      // the `Extractor` implementations.
+      String fileName = file.getFileName().toString();
+      if (fileName.startsWith("bugpattern-test")) {
+        bugPatternTests.add(Json.read(file, BugPatternTestCases.class));
+      } else if (fileName.startsWith("bugpattern")) {
+        bugPatterns.add(Json.read(file, BugPatternDocumentation.class));
+      } else if (fileName.startsWith("refaster-rule-collection-test")) {
+        refasterRuleCollectionTests.add(Json.read(file, RefasterTestCases.class));
+      } else {
+        // XXX: Handle differently?
+        throw new IllegalStateException("Unexpected file: " + fileName);
+      }
+
+      return FileVisitResult.CONTINUE;
+    }
+
+    private void writePages(Path projectRoot) throws IOException {
+      Path website = projectRoot.resolve("website");
+      writePages(
+          website.resolve("_bugpatterns"),
+          getJekyllBugPatternDescriptions(projectRoot),
+          JekyllBugPatternDescription::name);
+      writePages(
+          website.resolve("_refasterrules"),
+          getJekyllRefasterRuleCollectionDescription(),
+          JekyllRefasterRuleCollectionDescription::name);
+    }
+
+    private static <T> void writePages(
+        Path directory, ImmutableList<T> documents, Function<T, String> nameExtractor)
+        throws IOException {
+      for (T document : documents) {
+        Files.createDirectories(directory);
+        try (BufferedWriter writer =
+            Files.newBufferedWriter(
+                directory.resolve(nameExtractor.apply(document) + ".md"), UTF_8)) {
+          YAML_MAPPER.writeValue(writer, document);
+          writer.write("---");
+          writer.newLine();
+        }
+      }
+    }
+
+    private ImmutableList<JekyllBugPatternDescription> getJekyllBugPatternDescriptions(
+        Path projectRoot) {
+      ImmutableListMultimap<String, TestEntry> bugPatternTestCases =
+          bugPatternTests.stream()
+              .flatMap(testCases -> testCases.testCases().stream())
+              .collect(
+                  flatteningToImmutableListMultimap(
+                      BugPatternTestCase::classUnderTest, t -> t.entries().stream()));
+
+      return bugPatterns.stream()
+          .map(
+              b ->
+                  new AutoValue_JekyllCollectionGenerator_JekyllBugPatternDescription(
+                      b.name(),
+                      b.name(),
+                      b.summary(),
+                      b.severityLevel(),
+                      b.tags(),
+                      // XXX: Derive `Path` from filesytem.
+                      projectRoot.relativize(Path.of(b.source())).toString(),
+                      bugPatternTestCases.get(b.fullyQualifiedName()).stream()
+                          .filter(t -> t.type() == TestEntry.TestType.IDENTIFICATION)
+                          .map(t -> ((IdentificationTestEntry) t).code())
+                          .collect(toImmutableList()),
+                      bugPatternTestCases.get(b.fullyQualifiedName()).stream()
+                          .filter(t -> t.type() == TestEntry.TestType.REPLACEMENT)
+                          .map(t -> generateDiff((ReplacementTestEntry) t))
+                          .collect(toImmutableList())))
+          .collect(toImmutableList());
+    }
+
+    private ImmutableList<JekyllRefasterRuleCollectionDescription>
+        getJekyllRefasterRuleCollectionDescription() {
+      ImmutableTable<String, Boolean, List<RefasterTestCase>> refasterTests =
+          refasterRuleCollectionTests.stream()
+              .collect(
+                  toImmutableTable(
+                      RefasterTestCases::ruleCollection,
+                      RefasterTestCases::isInput,
+                      RefasterTestCases::testCases));
+
+      return refasterTests.rowMap().entrySet().stream()
+          .map(
+              c ->
+                  new AutoValue_JekyllCollectionGenerator_JekyllRefasterRuleCollectionDescription(
+                      c.getKey(),
+                      c.getKey(),
+                      // XXX: Derive severity from input.
+                      SUGGESTION,
+                      // XXX: Derive tags from input (or drop this feature).
+                      ImmutableList.of("Simplification"),
+                      // XXX: Derive source location from input.
+                      String.format(
+                          "error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/%s.java",
+                          c.getKey()),
+                      getRules(c.getValue().get(true), c.getValue().get(false))))
+          .collect(toImmutableList());
+    }
+
+    private static ImmutableList<JekyllRefasterRuleCollectionDescription.Rule> getRules(
+        @Nullable List<RefasterTestCase> inputTests, @Nullable List<RefasterTestCase> outputTests) {
+      ImmutableMap<String, String> inputs = indexRefasterTestData(inputTests);
+      ImmutableMap<String, String> outputs = indexRefasterTestData(outputTests);
+
+      return Sets.intersection(inputs.keySet(), outputs.keySet()).stream()
+          .map(
+              name ->
+                  new AutoValue_JekyllCollectionGenerator_JekyllRefasterRuleCollectionDescription_Rule(
+                      name,
+                      // XXX: Derive severity from input.
+                      SUGGESTION,
+                      // XXX: Derive tags from input (or drop this feature).
+                      ImmutableList.of("Simplification"),
+                      generateDiff(
+                          requireNonNull(inputs.get(name), "Input"),
+                          requireNonNull(outputs.get(name), "Output"))))
+          .collect(toImmutableList());
+    }
+
+    private static ImmutableMap<String, String> indexRefasterTestData(
+        @Nullable List<RefasterTestCase> data) {
+      return data == null
+          ? ImmutableMap.of()
+          : data.stream()
+              .collect(toImmutableMap(RefasterTestCase::name, RefasterTestCase::content));
+    }
+
+    private static String generateDiff(ReplacementTestEntry testEntry) {
+      return generateDiff(testEntry.input(), testEntry.output());
+    }
+
+    private static String generateDiff(String before, String after) {
+      // XXX: Extract splitter.
+      List<String> originalLines = LINE_SPLITTER.splitToList(before);
+      List<String> replacementLines = LINE_SPLITTER.splitToList(after);
+
+      Patch<String> diff = DiffUtils.diff(originalLines, replacementLines);
+
+      return UnifiedDiffUtils.generateUnifiedDiff(
+              "", "", originalLines, diff, Integer.MAX_VALUE / 2)
+          .stream()
+          .skip(3)
+          .collect(joining(System.lineSeparator()));
+    }
+  }
+
+  @AutoValue
+  abstract static class JekyllBugPatternDescription {
+    // XXX: Make this a derived property?
+    abstract String title();
+
+    abstract String name();
+
+    abstract String summary();
+
+    abstract SeverityLevel severity();
+
+    abstract ImmutableList<String> tags();
+
+    // XXX: The documentation could link to the original test code. Perhaps even with the correct
+    // line numbers.
+    abstract String source();
+
+    // XXX: The `identification` and `replacement` fields have odd names.
+    abstract ImmutableList<String> identification();
+
+    abstract ImmutableList<String> replacement();
+  }
+
+  @AutoValue
+  abstract static class JekyllRefasterRuleCollectionDescription {
+    // XXX: Make this a derived property?
+    abstract String title();
+
+    abstract String name();
+
+    abstract SeverityLevel severity();
+
+    abstract ImmutableList<String> tags();
+
+    // XXX: The documentation could link to the original test code. Perhaps even with the correct
+    // line numbers. If we do this, we should do the same for individual rules.
+    abstract String source();
+
+    abstract ImmutableList<Rule> rules();
+
+    @AutoValue
+    abstract static class Rule {
+      abstract String name();
+
+      abstract SeverityLevel severity();
+
+      abstract ImmutableList<String> tags();
+
+      abstract String diff();
+    }
+  }
+}

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

@@ -0,0 +1,45 @@
+package tech.picnic.errorprone.documentation;
+
+import com.fasterxml.jackson.annotation.JsonAutoDetect.Visibility;
+import com.fasterxml.jackson.annotation.PropertyAccessor;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.datatype.guava.GuavaModule;
+import com.fasterxml.jackson.module.paramnames.ParameterNamesModule;
+import com.google.errorprone.annotations.FormatMethod;
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.nio.file.Path;
+
+/**
+ * Utility class that offers mutually consistent JSON serialization and deserialization operations,
+ * without further specifying the exact schema used.
+ */
+final class Json {
+  private static final ObjectMapper OBJECT_MAPPER =
+      new ObjectMapper()
+          .setVisibility(PropertyAccessor.FIELD, Visibility.ANY)
+          .registerModules(new GuavaModule(), new ParameterNamesModule());
+
+  private Json() {}
+
+  static <T> T read(Path path, Class<T> clazz) {
+    try {
+      return OBJECT_MAPPER.readValue(path.toFile(), clazz);
+    } catch (IOException e) {
+      throw failure(e, "Failure reading from '%s'", path);
+    }
+  }
+
+  static <T> void write(Path path, T object) {
+    try {
+      OBJECT_MAPPER.writeValue(path.toFile(), object);
+    } catch (IOException e) {
+      throw failure(e, "Failure writing to '%s'", path);
+    }
+  }
+
+  @FormatMethod
+  private static UncheckedIOException failure(IOException cause, String format, Object... args) {
+    return new UncheckedIOException(String.format(format, args), cause);
+  }
+}

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/main/java/tech/picnic/errorprone/documentation/models/RefasterTemplateCollectionData.java

@@ -0,0 +1,27 @@
+package tech.picnic.errorprone.documentation.models;
+
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+import com.google.auto.value.AutoValue;
+import com.google.common.collect.ImmutableList;
+
+/**
+ * Object containing all data related to a Refaster template collection. This is solely used for
+ * serialization.
+ */
+// XXX: This class is not yet used.
+@AutoValue
+@JsonDeserialize(as = AutoValue_RefasterTemplateCollectionData.class)
+abstract class RefasterTemplateCollectionData {
+  static RefasterTemplateCollectionData create(
+      String name, String description, String link, ImmutableList<RefasterTemplateData> templates) {
+    return new AutoValue_RefasterTemplateCollectionData(name, description, link, templates);
+  }
+
+  abstract String name();
+
+  abstract String description();
+
+  abstract String link();
+
+  abstract ImmutableList<RefasterTemplateData> templates();
+}

documentation-support/src/main/java/tech/picnic/errorprone/documentation/models/RefasterTemplateData.java

@@ -0,0 +1,23 @@
+package tech.picnic.errorprone.documentation.models;
+
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+import com.google.auto.value.AutoValue;
+import com.google.errorprone.BugPattern.SeverityLevel;
+
+// XXX: This class is not yet used.
+@AutoValue
+@JsonDeserialize(as = AutoValue_RefasterTemplateData.class)
+abstract class RefasterTemplateData {
+  static RefasterTemplateData create(
+      String name, String description, String link, SeverityLevel severityLevel) {
+    return new AutoValue_RefasterTemplateData(name, description, link, severityLevel);
+  }
+
+  abstract String name();
+
+  abstract String description();
+
+  abstract String link();
+
+  abstract SeverityLevel severityLevel();
+}

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

@@ -1,13 +1,17 @@
 package tech.picnic.errorprone.documentation;
 
-import static java.nio.charset.StandardCharsets.UTF_8;
+import static com.google.errorprone.BugPattern.SeverityLevel.ERROR;
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
 import static org.assertj.core.api.Assertions.assertThat;
 
-import com.google.common.io.Resources;
-import java.io.IOException;
+import com.google.common.collect.ImmutableList;
+import com.google.errorprone.BugPattern;
+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.BugPatternExtractor.BugPatternDocumentation;
 
 final class BugPatternExtractorTest {
   @Test
@@ -23,7 +27,7 @@ final class BugPatternExtractorTest {
   }
 
   @Test
-  void minimalBugPattern(@TempDir Path outputDirectory) throws IOException {
+  void minimalBugPattern(@TempDir Path outputDirectory) {
     Compilation.compileWithDocumentationGenerator(
         outputDirectory,
         "MinimalBugChecker.java",
@@ -36,11 +40,25 @@ final class BugPatternExtractorTest {
         "@BugPattern(summary = \"MinimalBugChecker summary\", severity = SeverityLevel.ERROR)",
         "public final class MinimalBugChecker extends BugChecker {}");
 
-    verifyGeneratedFileContent(outputDirectory, "MinimalBugChecker");
+    verifyGeneratedFileContent(
+        outputDirectory,
+        "MinimalBugChecker",
+        BugPatternDocumentation.create(
+            URI.create("file:///MinimalBugChecker.java"),
+            "pkg.MinimalBugChecker",
+            "MinimalBugChecker",
+            ImmutableList.of(),
+            "",
+            ImmutableList.of(),
+            "MinimalBugChecker summary",
+            "",
+            ERROR,
+            /* canDisable= */ true,
+            ImmutableList.of(SuppressWarnings.class.getCanonicalName())));
   }
 
   @Test
-  void completeBugPattern(@TempDir Path outputDirectory) throws IOException {
+  void completeBugPattern(@TempDir Path outputDirectory) {
     Compilation.compileWithDocumentationGenerator(
         outputDirectory,
         "CompleteBugChecker.java",
@@ -64,11 +82,25 @@ final class BugPatternExtractorTest {
         "    suppressionAnnotations = {BugPattern.class, Test.class})",
         "public final class CompleteBugChecker extends BugChecker {}");
 
-    verifyGeneratedFileContent(outputDirectory, "CompleteBugChecker");
+    verifyGeneratedFileContent(
+        outputDirectory,
+        "CompleteBugChecker",
+        BugPatternDocumentation.create(
+            URI.create("file:///CompleteBugChecker.java"),
+            "pkg.CompleteBugChecker",
+            "OtherName",
+            ImmutableList.of("Check"),
+            "https://error-prone.picnic.tech",
+            ImmutableList.of("Simplification"),
+            "CompleteBugChecker summary",
+            "Example explanation",
+            SUGGESTION,
+            /* canDisable= */ false,
+            ImmutableList.of(BugPattern.class.getCanonicalName(), "org.junit.jupiter.api.Test")));
   }
 
   @Test
-  void undocumentedSuppressionBugPattern(@TempDir Path outputDirectory) throws IOException {
+  void undocumentedSuppressionBugPattern(@TempDir Path outputDirectory) {
     Compilation.compileWithDocumentationGenerator(
         outputDirectory,
         "UndocumentedSuppressionBugPattern.java",
@@ -84,23 +116,27 @@ final class BugPatternExtractorTest {
         "    documentSuppression = false)",
         "public final class UndocumentedSuppressionBugPattern extends BugChecker {}");
 
-    verifyGeneratedFileContent(outputDirectory, "UndocumentedSuppressionBugPattern");
+    verifyGeneratedFileContent(
+        outputDirectory,
+        "UndocumentedSuppressionBugPattern",
+        BugPatternDocumentation.create(
+            URI.create("file:///UndocumentedSuppressionBugPattern.java"),
+            "pkg.UndocumentedSuppressionBugPattern",
+            "UndocumentedSuppressionBugPattern",
+            ImmutableList.of(),
+            "",
+            ImmutableList.of(),
+            "UndocumentedSuppressionBugPattern summary",
+            "",
+            WARNING,
+            /* canDisable= */ true,
+            ImmutableList.of()));
   }
 
-  private static void verifyGeneratedFileContent(Path outputDirectory, String testClass)
-      throws IOException {
-    String resourceName = String.format("bugpattern-%s.json", testClass);
-    assertThat(outputDirectory.resolve(resourceName))
-        .content(UTF_8)
-        .isEqualToIgnoringWhitespace(
-            getResource(
-                String.join("-", BugPatternExtractorTest.class.getSimpleName(), resourceName)));
-  }
-
-  // XXX: Once we support only JDK 15+, drop this method in favour of including the resources as
-  // text blocks in this class.
-  private static String getResource(String resourceName) throws IOException {
-    return Resources.toString(
-        Resources.getResource(BugPatternExtractorTest.class, resourceName), UTF_8);
+  private static void verifyGeneratedFileContent(
+      Path outputDirectory, String testClass, BugPatternDocumentation expected) {
+    assertThat(outputDirectory.resolve(String.format("bugpattern-%s.json", testClass)))
+        .exists()
+        .returns(expected, path -> Json.read(path, BugPatternDocumentation.class));
   }
 }

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

@@ -1,13 +1,16 @@
 package tech.picnic.errorprone.documentation;
 
-import static java.nio.charset.StandardCharsets.UTF_8;
 import static org.assertj.core.api.Assertions.assertThat;
 
-import com.google.common.io.Resources;
-import java.io.IOException;
+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.BugPatternTestExtractor.BugPatternTestCase;
+import tech.picnic.errorprone.documentation.BugPatternTestExtractor.BugPatternTestCases;
+import tech.picnic.errorprone.documentation.BugPatternTestExtractor.IdentificationTestEntry;
+import tech.picnic.errorprone.documentation.BugPatternTestExtractor.ReplacementTestEntry;
 
 final class BugPatternTestExtractorTest {
   @Test
@@ -246,7 +249,7 @@ final class BugPatternTestExtractorTest {
   }
 
   @Test
-  void singleFileCompilationTestHelper(@TempDir Path outputDirectory) throws IOException {
+  void singleFileCompilationTestHelper(@TempDir Path outputDirectory) {
     Compilation.compileWithDocumentationGenerator(
         outputDirectory,
         "SingleFileCompilationTestHelperTest.java",
@@ -263,12 +266,22 @@ final class BugPatternTestExtractorTest {
         "  }",
         "}");
 
-    verifyGeneratedFileContent(outputDirectory, "SingleFileCompilationTestHelperTest");
+    verifyGeneratedFileContent(
+        outputDirectory,
+        "SingleFileCompilationTestHelperTest",
+        BugPatternTestCases.create(
+            URI.create("file:///SingleFileCompilationTestHelperTest.java"),
+            "SingleFileCompilationTestHelperTest",
+            ImmutableList.of(
+                BugPatternTestCase.create(
+                    "SingleFileCompilationTestHelperTest.TestChecker",
+                    ImmutableList.of(
+                        IdentificationTestEntry.create(
+                            "A.java", "// BUG: Diagnostic contains:\nclass A {}\n"))))));
   }
 
   @Test
-  void singleFileCompilationTestHelperWithSetArgs(@TempDir Path outputDirectory)
-      throws IOException {
+  void singleFileCompilationTestHelperWithSetArgs(@TempDir Path outputDirectory) {
     Compilation.compileWithDocumentationGenerator(
         outputDirectory,
         "SingleFileCompilationTestHelperWithSetArgsTest.java",
@@ -286,11 +299,22 @@ final class BugPatternTestExtractorTest {
         "  }",
         "}");
 
-    verifyGeneratedFileContent(outputDirectory, "SingleFileCompilationTestHelperWithSetArgsTest");
+    verifyGeneratedFileContent(
+        outputDirectory,
+        "SingleFileCompilationTestHelperWithSetArgsTest",
+        BugPatternTestCases.create(
+            URI.create("file:///SingleFileCompilationTestHelperWithSetArgsTest.java"),
+            "SingleFileCompilationTestHelperWithSetArgsTest",
+            ImmutableList.of(
+                BugPatternTestCase.create(
+                    "SingleFileCompilationTestHelperWithSetArgsTest.TestChecker",
+                    ImmutableList.of(
+                        IdentificationTestEntry.create(
+                            "A.java", "// BUG: Diagnostic contains:\nclass A {}\n"))))));
   }
 
   @Test
-  void multiFileCompilationTestHelper(@TempDir Path outputDirectory) throws IOException {
+  void multiFileCompilationTestHelper(@TempDir Path outputDirectory) {
     Compilation.compileWithDocumentationGenerator(
         outputDirectory,
         "MultiFileCompilationTestHelperTest.java",
@@ -308,11 +332,24 @@ final class BugPatternTestExtractorTest {
         "  }",
         "}");
 
-    verifyGeneratedFileContent(outputDirectory, "MultiFileCompilationTestHelperTest");
+    verifyGeneratedFileContent(
+        outputDirectory,
+        "MultiFileCompilationTestHelperTest",
+        BugPatternTestCases.create(
+            URI.create("file:///MultiFileCompilationTestHelperTest.java"),
+            "MultiFileCompilationTestHelperTest",
+            ImmutableList.of(
+                BugPatternTestCase.create(
+                    "MultiFileCompilationTestHelperTest.TestChecker",
+                    ImmutableList.of(
+                        IdentificationTestEntry.create(
+                            "A.java", "// BUG: Diagnostic contains:\nclass A {}\n"),
+                        IdentificationTestEntry.create(
+                            "B.java", "// BUG: Diagnostic contains:\nclass B {}\n"))))));
   }
 
   @Test
-  void singleFileBugCheckerRefactoringTestHelper(@TempDir Path outputDirectory) throws IOException {
+  void singleFileBugCheckerRefactoringTestHelper(@TempDir Path outputDirectory) {
     Compilation.compileWithDocumentationGenerator(
         outputDirectory,
         "SingleFileBugCheckerRefactoringTestHelperTest.java",
@@ -330,12 +367,23 @@ final class BugPatternTestExtractorTest {
         "  }",
         "}");
 
-    verifyGeneratedFileContent(outputDirectory, "SingleFileBugCheckerRefactoringTestHelperTest");
+    verifyGeneratedFileContent(
+        outputDirectory,
+        "SingleFileBugCheckerRefactoringTestHelperTest",
+        BugPatternTestCases.create(
+            URI.create("file:///SingleFileBugCheckerRefactoringTestHelperTest.java"),
+            "SingleFileBugCheckerRefactoringTestHelperTest",
+            ImmutableList.of(
+                BugPatternTestCase.create(
+                    "SingleFileBugCheckerRefactoringTestHelperTest.TestChecker",
+                    ImmutableList.of(
+                        ReplacementTestEntry.create(
+                            "A.java", "class A {}\n", "class A { /* This is a change. */ }\n"))))));
   }
 
   @Test
   void singleFileBugCheckerRefactoringTestHelperWithSetArgsFixChooserAndCustomTestMode(
-      @TempDir Path outputDirectory) throws IOException {
+      @TempDir Path outputDirectory) {
     Compilation.compileWithDocumentationGenerator(
         outputDirectory,
         "SingleFileBugCheckerRefactoringTestHelperWithSetArgsFixChooserAndCustomTestModeTest.java",
@@ -359,11 +407,21 @@ final class BugPatternTestExtractorTest {
 
     verifyGeneratedFileContent(
         outputDirectory,
-        "SingleFileBugCheckerRefactoringTestHelperWithSetArgsFixChooserAndCustomTestModeTest");
+        "SingleFileBugCheckerRefactoringTestHelperWithSetArgsFixChooserAndCustomTestModeTest",
+        BugPatternTestCases.create(
+            URI.create(
+                "file:///SingleFileBugCheckerRefactoringTestHelperWithSetArgsFixChooserAndCustomTestModeTest.java"),
+            "SingleFileBugCheckerRefactoringTestHelperWithSetArgsFixChooserAndCustomTestModeTest",
+            ImmutableList.of(
+                BugPatternTestCase.create(
+                    "SingleFileBugCheckerRefactoringTestHelperWithSetArgsFixChooserAndCustomTestModeTest.TestChecker",
+                    ImmutableList.of(
+                        ReplacementTestEntry.create(
+                            "A.java", "class A {}\n", "class A { /* This is a change. */ }\n"))))));
   }
 
   @Test
-  void multiFileBugCheckerRefactoringTestHelper(@TempDir Path outputDirectory) throws IOException {
+  void multiFileBugCheckerRefactoringTestHelper(@TempDir Path outputDirectory) {
     Compilation.compileWithDocumentationGenerator(
         outputDirectory,
         "MultiFileBugCheckerRefactoringTestHelperTest.java",
@@ -383,12 +441,24 @@ final class BugPatternTestExtractorTest {
         "  }",
         "}");
 
-    verifyGeneratedFileContent(outputDirectory, "MultiFileBugCheckerRefactoringTestHelperTest");
+    verifyGeneratedFileContent(
+        outputDirectory,
+        "MultiFileBugCheckerRefactoringTestHelperTest",
+        BugPatternTestCases.create(
+            URI.create("file:///MultiFileBugCheckerRefactoringTestHelperTest.java"),
+            "MultiFileBugCheckerRefactoringTestHelperTest",
+            ImmutableList.of(
+                BugPatternTestCase.create(
+                    "MultiFileBugCheckerRefactoringTestHelperTest.TestChecker",
+                    ImmutableList.of(
+                        ReplacementTestEntry.create(
+                            "A.java", "class A {}\n", "class A { /* This is a change. */ }\n"),
+                        ReplacementTestEntry.create(
+                            "B.java", "class B {}\n", "class B { /* This is a change. */ }\n"))))));
   }
 
   @Test
-  void compilationAndBugCheckerRefactoringTestHelpers(@TempDir Path outputDirectory)
-      throws IOException {
+  void compilationAndBugCheckerRefactoringTestHelpers(@TempDir Path outputDirectory) {
     Compilation.compileWithDocumentationGenerator(
         outputDirectory,
         "CompilationAndBugCheckerRefactoringTestHelpersTest.java",
@@ -412,12 +482,27 @@ final class BugPatternTestExtractorTest {
         "}");
 
     verifyGeneratedFileContent(
-        outputDirectory, "CompilationAndBugCheckerRefactoringTestHelpersTest");
+        outputDirectory,
+        "CompilationAndBugCheckerRefactoringTestHelpersTest",
+        BugPatternTestCases.create(
+            URI.create("file:///CompilationAndBugCheckerRefactoringTestHelpersTest.java"),
+            "CompilationAndBugCheckerRefactoringTestHelpersTest",
+            ImmutableList.of(
+                BugPatternTestCase.create(
+                    "CompilationAndBugCheckerRefactoringTestHelpersTest.TestChecker",
+                    ImmutableList.of(
+                        IdentificationTestEntry.create(
+                            "A.java", "// BUG: Diagnostic contains:\nclass A {}\n"))),
+                BugPatternTestCase.create(
+                    "CompilationAndBugCheckerRefactoringTestHelpersTest.TestChecker",
+                    ImmutableList.of(
+                        ReplacementTestEntry.create(
+                            "A.java", "class A {}\n", "class A { /* This is a change. */ }\n"))))));
   }
 
   @Test
   void compilationAndBugCheckerRefactoringTestHelpersWithCustomCheckerPackageAndNames(
-      @TempDir Path outputDirectory) throws IOException {
+      @TempDir Path outputDirectory) {
     Compilation.compileWithDocumentationGenerator(
         outputDirectory,
         "CompilationAndBugCheckerRefactoringTestHelpersWithCustomCheckerPackageAndNamesTest.java",
@@ -446,23 +531,28 @@ final class BugPatternTestExtractorTest {
 
     verifyGeneratedFileContent(
         outputDirectory,
-        "CompilationAndBugCheckerRefactoringTestHelpersWithCustomCheckerPackageAndNamesTest");
+        "CompilationAndBugCheckerRefactoringTestHelpersWithCustomCheckerPackageAndNamesTest",
+        BugPatternTestCases.create(
+            URI.create(
+                "file:///CompilationAndBugCheckerRefactoringTestHelpersWithCustomCheckerPackageAndNamesTest.java"),
+            "pkg.CompilationAndBugCheckerRefactoringTestHelpersWithCustomCheckerPackageAndNamesTest",
+            ImmutableList.of(
+                BugPatternTestCase.create(
+                    "pkg.CompilationAndBugCheckerRefactoringTestHelpersWithCustomCheckerPackageAndNamesTest.CustomTestChecker",
+                    ImmutableList.of(
+                        IdentificationTestEntry.create(
+                            "A.java", "// BUG: Diagnostic contains:\nclass A {}\n"))),
+                BugPatternTestCase.create(
+                    "pkg.CompilationAndBugCheckerRefactoringTestHelpersWithCustomCheckerPackageAndNamesTest.CustomTestChecker2",
+                    ImmutableList.of(
+                        ReplacementTestEntry.create(
+                            "A.java", "class A {}\n", "class A { /* This is a change. */ }\n"))))));
   }
 
-  private static void verifyGeneratedFileContent(Path outputDirectory, String testClass)
-      throws IOException {
-    String resourceName = String.format("bugpattern-test-%s.json", testClass);
-    assertThat(outputDirectory.resolve(resourceName))
-        .content(UTF_8)
-        .isEqualToIgnoringWhitespace(
-            getResource(
-                String.join("-", BugPatternTestExtractorTest.class.getSimpleName(), resourceName)));
-  }
-
-  // XXX: Once we support only JDK 15+, drop this method in favour of including the resources as
-  // text blocks in this class.
-  private static String getResource(String resourceName) throws IOException {
-    return Resources.toString(
-        Resources.getResource(BugPatternTestExtractorTest.class, resourceName), UTF_8);
+  private static void verifyGeneratedFileContent(
+      Path outputDirectory, String testClass, BugPatternTestCases expected) {
+    assertThat(outputDirectory.resolve(String.format("bugpattern-test-%s.json", testClass)))
+        .exists()
+        .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()));
 
@@ -93,13 +93,20 @@ final class DocumentationGeneratorTaskListenerTest {
         "DocumentationGeneratorTaskListenerTestClass.java",
         "class DocumentationGeneratorTaskListenerTestClass {}");
 
-    // XXX: Once we support only JDK 15+, use a text block for the `expected` string.
     assertThat(
             outputDirectory.resolve(
                 "documentation-generator-task-listener-test-DocumentationGeneratorTaskListenerTestClass.json"))
         .content(UTF_8)
         .isEqualToIgnoringWhitespace(
-            "{\"className\":\"DocumentationGeneratorTaskListenerTestClass\",\"path\":[\"CLASS: DocumentationGeneratorTaskListenerTestClass\",\"COMPILATION_UNIT\"]}");
+            """
+            {
+              "className": "DocumentationGeneratorTaskListenerTestClass",
+              "path": [
+                "CLASS: DocumentationGeneratorTaskListenerTestClass",
+                "COMPILATION_UNIT"
+              ]
+            }
+            """);
   }
 
   @Immutable
@@ -125,8 +132,8 @@ final class DocumentationGeneratorTaskListenerTest {
     }
 
     private static String describeTree(Tree tree) {
-      return (tree instanceof ClassTree)
-          ? String.join(": ", String.valueOf(tree.getKind()), ((ClassTree) tree).getSimpleName())
+      return (tree instanceof ClassTree clazz)
+          ? String.join(": ", String.valueOf(tree.getKind()), clazz.getSimpleName())
           : tree.getKind().toString();
     }
   }

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

@@ -0,0 +1,13 @@
+package tech.picnic.errorprone.documentation;
+
+import java.io.IOException;
+import org.junit.jupiter.api.Test;
+
+// XXX: Implement tests.
+final class JekyllCollectionGeneratorTest {
+  @Test
+  void foo() throws IOException {
+    JekyllCollectionGenerator.main(
+        new String[] {"/home/sschroevers/workspace/picnic/error-prone-support"});
+  }
+}

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

@@ -0,0 +1,62 @@
+package tech.picnic.errorprone.documentation;
+
+import static java.nio.charset.StandardCharsets.UTF_8;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+import com.google.auto.value.AutoValue;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+final class JsonTest {
+  private static final TestObject TEST_OBJECT = new AutoValue_JsonTest_TestObject("foo", 42);
+  private static final String TEST_JSON = "{\"string\":\"foo\",\"number\":42}";
+
+  @Test
+  void write(@TempDir Path directory) {
+    Path file = directory.resolve("test.json");
+
+    Json.write(file, TEST_OBJECT);
+
+    assertThat(file).content(UTF_8).isEqualTo(TEST_JSON);
+  }
+
+  @Test
+  void writeFailure(@TempDir Path directory) {
+    assertThatThrownBy(() -> Json.write(directory, TEST_OBJECT))
+        .isInstanceOf(UncheckedIOException.class)
+        .hasMessageContaining("Failure writing to '%s'", directory)
+        .hasCauseInstanceOf(FileNotFoundException.class);
+  }
+
+  @Test
+  void read(@TempDir Path directory) throws IOException {
+    Path file = directory.resolve("test.json");
+
+    Files.writeString(file, TEST_JSON, UTF_8);
+
+    assertThat(Json.read(file, TestObject.class)).isEqualTo(TEST_OBJECT);
+  }
+
+  @Test
+  void readFailure(@TempDir Path directory) {
+    assertThatThrownBy(() -> Json.read(directory, TestObject.class))
+        .isInstanceOf(UncheckedIOException.class)
+        .hasMessageContaining("Failure reading from '%s'", directory)
+        .hasCauseInstanceOf(FileNotFoundException.class);
+  }
+
+  @AutoValue
+  @JsonDeserialize(as = AutoValue_JsonTest_TestObject.class)
+  abstract static class TestObject {
+    abstract String string();
+
+    abstract int number();
+  }
+}

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));
+  }
+}

documentation-support/src/test/resources/tech/picnic/errorprone/documentation/BugPatternExtractorTest-bugpattern-CompleteBugChecker.json

@@ -1,19 +0,0 @@
-{
-  "fullyQualifiedName": "pkg.CompleteBugChecker",
-  "name": "OtherName",
-  "altNames": [
-    "Check"
-  ],
-  "link": "https://error-prone.picnic.tech",
-  "tags": [
-    "Simplification"
-  ],
-  "summary": "CompleteBugChecker summary",
-  "explanation": "Example explanation",
-  "severityLevel": "SUGGESTION",
-  "canDisable": false,
-  "suppressionAnnotations": [
-    "com.google.errorprone.BugPattern",
-    "org.junit.jupiter.api.Test"
-  ]
-}

documentation-support/src/test/resources/tech/picnic/errorprone/documentation/BugPatternExtractorTest-bugpattern-MinimalBugChecker.json

@@ -1,14 +0,0 @@
-{
-  "fullyQualifiedName": "pkg.MinimalBugChecker",
-  "name": "MinimalBugChecker",
-  "altNames": [],
-  "link": "",
-  "tags": [],
-  "summary": "MinimalBugChecker summary",
-  "explanation": "",
-  "severityLevel": "ERROR",
-  "canDisable": true,
-  "suppressionAnnotations": [
-    "java.lang.SuppressWarnings"
-  ]
-}

documentation-support/src/test/resources/tech/picnic/errorprone/documentation/BugPatternExtractorTest-bugpattern-UndocumentedSuppressionBugPattern.json

@@ -1,12 +0,0 @@
-{
-  "fullyQualifiedName": "pkg.UndocumentedSuppressionBugPattern",
-  "name": "UndocumentedSuppressionBugPattern",
-  "altNames": [],
-  "link": "",
-  "tags": [],
-  "summary": "UndocumentedSuppressionBugPattern summary",
-  "explanation": "",
-  "severityLevel": "WARNING",
-  "canDisable": true,
-  "suppressionAnnotations": []
-}

documentation-support/src/test/resources/tech/picnic/errorprone/documentation/BugPatternTestExtractorTest-bugpattern-test-CompilationAndBugCheckerRefactoringTestHelpersTest.json

@@ -1,24 +0,0 @@
-{
-  "testClass": "CompilationAndBugCheckerRefactoringTestHelpersTest",
-  "testCases": [
-    {
-      "classUnderTest": "CompilationAndBugCheckerRefactoringTestHelpersTest.TestChecker",
-      "entries": [
-        {
-          "path": "A.java",
-          "code": "// BUG: Diagnostic contains:\nclass A {}\n"
-        }
-      ]
-    },
-    {
-      "classUnderTest": "CompilationAndBugCheckerRefactoringTestHelpersTest.TestChecker",
-      "entries": [
-        {
-          "path": "A.java",
-          "input": "class A {}\n",
-          "output": "class A { /* This is a change. */ }\n"
-        }
-      ]
-    }
-  ]
-}

documentation-support/src/test/resources/tech/picnic/errorprone/documentation/BugPatternTestExtractorTest-bugpattern-test-CompilationAndBugCheckerRefactoringTestHelpersWithCustomCheckerPackageAndNamesTest.json

@@ -1,24 +0,0 @@
-{
-  "testClass": "pkg.CompilationAndBugCheckerRefactoringTestHelpersWithCustomCheckerPackageAndNamesTest",
-  "testCases": [
-    {
-      "classUnderTest": "pkg.CompilationAndBugCheckerRefactoringTestHelpersWithCustomCheckerPackageAndNamesTest.CustomTestChecker",
-      "entries": [
-        {
-          "path": "A.java",
-          "code": "// BUG: Diagnostic contains:\nclass A {}\n"
-        }
-      ]
-    },
-    {
-      "classUnderTest": "pkg.CompilationAndBugCheckerRefactoringTestHelpersWithCustomCheckerPackageAndNamesTest.CustomTestChecker2",
-      "entries": [
-        {
-          "path": "A.java",
-          "input": "class A {}\n",
-          "output": "class A { /* This is a change. */ }\n"
-        }
-      ]
-    }
-  ]
-}

documentation-support/src/test/resources/tech/picnic/errorprone/documentation/BugPatternTestExtractorTest-bugpattern-test-MultiFileBugCheckerRefactoringTestHelperTest.json

@@ -1,20 +0,0 @@
-{
-  "testClass": "MultiFileBugCheckerRefactoringTestHelperTest",
-  "testCases": [
-    {
-      "classUnderTest": "MultiFileBugCheckerRefactoringTestHelperTest.TestChecker",
-      "entries": [
-        {
-          "path": "A.java",
-          "input": "class A {}\n",
-          "output": "class A { /* This is a change. */ }\n"
-        },
-        {
-          "path": "B.java",
-          "input": "class B {}\n",
-          "output": "class B { /* This is a change. */ }\n"
-        }
-      ]
-    }
-  ]
-}

documentation-support/src/test/resources/tech/picnic/errorprone/documentation/BugPatternTestExtractorTest-bugpattern-test-MultiFileCompilationTestHelperTest.json

@@ -1,18 +0,0 @@
-{
-  "testClass": "MultiFileCompilationTestHelperTest",
-  "testCases": [
-    {
-      "classUnderTest": "MultiFileCompilationTestHelperTest.TestChecker",
-      "entries": [
-        {
-          "path": "A.java",
-          "code": "// BUG: Diagnostic contains:\nclass A {}\n"
-        },
-        {
-          "path": "B.java",
-          "code": "// BUG: Diagnostic contains:\nclass B {}\n"
-        }
-      ]
-    }
-  ]
-}

documentation-support/src/test/resources/tech/picnic/errorprone/documentation/BugPatternTestExtractorTest-bugpattern-test-SingleFileBugCheckerRefactoringTestHelperTest.json

@@ -1,15 +0,0 @@
-{
-  "testClass": "SingleFileBugCheckerRefactoringTestHelperTest",
-  "testCases": [
-    {
-      "classUnderTest": "SingleFileBugCheckerRefactoringTestHelperTest.TestChecker",
-      "entries": [
-        {
-          "path": "A.java",
-          "input": "class A {}\n",
-          "output": "class A { /* This is a change. */ }\n"
-        }
-      ]
-    }
-  ]
-}

documentation-support/src/test/resources/tech/picnic/errorprone/documentation/BugPatternTestExtractorTest-bugpattern-test-SingleFileBugCheckerRefactoringTestHelperWithSetArgsFixChooserAndCustomTestModeTest.json

@@ -1,15 +0,0 @@
-{
-  "testClass": "SingleFileBugCheckerRefactoringTestHelperWithSetArgsFixChooserAndCustomTestModeTest",
-  "testCases": [
-    {
-      "classUnderTest": "SingleFileBugCheckerRefactoringTestHelperWithSetArgsFixChooserAndCustomTestModeTest.TestChecker",
-      "entries": [
-        {
-          "path": "A.java",
-          "input": "class A {}\n",
-          "output": "class A { /* This is a change. */ }\n"
-        }
-      ]
-    }
-  ]
-}

documentation-support/src/test/resources/tech/picnic/errorprone/documentation/BugPatternTestExtractorTest-bugpattern-test-SingleFileCompilationTestHelperTest.json

@@ -1,14 +0,0 @@
-{
-  "testClass": "SingleFileCompilationTestHelperTest",
-  "testCases": [
-    {
-      "classUnderTest": "SingleFileCompilationTestHelperTest.TestChecker",
-      "entries": [
-        {
-          "path": "A.java",
-          "code": "// BUG: Diagnostic contains:\nclass A {}\n"
-        }
-      ]
-    }
-  ]
-}

documentation-support/src/test/resources/tech/picnic/errorprone/documentation/BugPatternTestExtractorTest-bugpattern-test-SingleFileCompilationTestHelperWithSetArgsTest.json

@@ -1,14 +0,0 @@
-{
-  "testClass": "SingleFileCompilationTestHelperWithSetArgsTest",
-  "testCases": [
-    {
-      "classUnderTest": "SingleFileCompilationTestHelperWithSetArgsTest.TestChecker",
-      "entries": [
-        {
-          "path": "A.java",
-          "code": "// BUG: Diagnostic contains:\nclass A {}\n"
-        }
-      ]
-    }
-  ]
-}

error-prone-contrib/pom.xml

@@ -5,40 +5,16 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.14.1-SNAPSHOT</version>
+        <version>0.21.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>error-prone-contrib</artifactId>
 
     <name>Picnic :: Error Prone Support :: Contrib</name>
     <description>Extra Error Prone plugins by Picnic.</description>
+    <url>https://error-prone.picnic.tech</url>
 
     <dependencies>
-        <dependency>
-            <groupId>${groupId.error-prone}</groupId>
-            <artifactId>error_prone_annotation</artifactId>
-            <scope>provided</scope>
-        </dependency>
-        <dependency>
-            <groupId>${groupId.error-prone}</groupId>
-            <artifactId>error_prone_annotations</artifactId>
-            <scope>provided</scope>
-        </dependency>
-        <dependency>
-            <groupId>${groupId.error-prone}</groupId>
-            <artifactId>error_prone_check_api</artifactId>
-            <scope>provided</scope>
-        </dependency>
-        <dependency>
-            <groupId>${groupId.error-prone}</groupId>
-            <artifactId>error_prone_core</artifactId>
-            <scope>provided</scope>
-        </dependency>
-        <dependency>
-            <groupId>${groupId.error-prone}</groupId>
-            <artifactId>error_prone_test_helpers</artifactId>
-            <scope>provided</scope>
-        </dependency>
         <dependency>
             <groupId>${project.groupId}</groupId>
             <artifactId>documentation-support</artifactId>
@@ -47,10 +23,19 @@
             `annotationProcessorPaths` configuration below. -->
             <scope>provided</scope>
         </dependency>
+        <dependency>
+            <groupId>${project.groupId}</groupId>
+            <artifactId>error-prone-utils</artifactId>
+        </dependency>
         <dependency>
             <groupId>${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>
@@ -60,11 +45,11 @@
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-annotations</artifactId>
-            <scope>test</scope>
+            <scope>provided</scope>
         </dependency>
         <dependency>
-            <groupId>com.google.auto</groupId>
-            <artifactId>auto-common</artifactId>
+            <groupId>com.github.ben-manes.caffeine</groupId>
+            <artifactId>caffeine</artifactId>
             <scope>provided</scope>
         </dependency>
         <dependency>
@@ -78,14 +63,40 @@
             <scope>provided</scope>
         </dependency>
         <dependency>
-            <groupId>com.google.googlejavaformat</groupId>
-            <artifactId>google-java-format</artifactId>
+            <groupId>com.google.errorprone</groupId>
+            <artifactId>error_prone_annotation</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.errorprone</groupId>
+            <artifactId>error_prone_annotations</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.errorprone</groupId>
+            <artifactId>error_prone_check_api</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.errorprone</groupId>
+            <artifactId>error_prone_core</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.errorprone</groupId>
+            <artifactId>error_prone_test_helpers</artifactId>
+            <scope>provided</scope>
         </dependency>
         <dependency>
             <groupId>com.google.guava</groupId>
             <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>
@@ -126,6 +137,11 @@
             <artifactId>jakarta.servlet-api</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>javax.annotation</groupId>
+            <artifactId>javax.annotation-api</artifactId>
+            <scope>provided</scope>
+        </dependency>
         <dependency>
             <groupId>javax.inject</groupId>
             <artifactId>javax.inject</artifactId>
@@ -151,6 +167,11 @@
             <artifactId>value-annotations</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.jooq</groupId>
+            <artifactId>jooq</artifactId>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>org.jspecify</groupId>
             <artifactId>jspecify</artifactId>
@@ -161,6 +182,8 @@
             <artifactId>junit-jupiter-api</artifactId>
             <scope>provided</scope>
         </dependency>
+        <!-- XXX: Explicitly declared as a workaround for
+        https://github.com/pitest/pitest-junit5-plugin/issues/105. -->
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-engine</artifactId>
@@ -181,6 +204,31 @@
             <artifactId>mongodb-driver-core</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.openrewrite</groupId>
+            <artifactId>rewrite-core</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.openrewrite</groupId>
+            <artifactId>rewrite-java</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.openrewrite</groupId>
+            <artifactId>rewrite-java-17</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.openrewrite</groupId>
+            <artifactId>rewrite-templating</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.openrewrite</groupId>
+            <artifactId>rewrite-test</artifactId>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>org.reactivestreams</groupId>
             <artifactId>reactive-streams</artifactId>
@@ -216,6 +264,11 @@
             <artifactId>spring-boot-test</artifactId>
             <scope>provided</scope>
         </dependency>
+        <dependency>
+            <groupId>org.springframework.security</groupId>
+            <artifactId>spring-security-core</artifactId>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>org.testng</groupId>
             <artifactId>testng</artifactId>
@@ -231,6 +284,9 @@
                     <artifactId>maven-compiler-plugin</artifactId>
                     <configuration>
                         <annotationProcessorPaths combine.children="append">
+                            <!-- XXX: Drop the version declarations once
+                            properly supported. See
+                            https://youtrack.jetbrains.com/issue/IDEA-342187. -->
                             <path>
                                 <groupId>${project.groupId}</groupId>
                                 <artifactId>documentation-support</artifactId>
@@ -248,10 +304,58 @@
                             </path>
                         </annotationProcessorPaths>
                         <compilerArgs combine.children="append">
-                            <arg>-Xplugin:RefasterRuleCompiler</arg>
                             <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/AmbiguousJsonCreator.java

@@ -4,7 +4,7 @@ import static com.google.errorprone.BugPattern.LinkType.CUSTOM;
 import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
 import static com.google.errorprone.BugPattern.StandardTags.LIKELY_ERROR;
 import static com.google.errorprone.matchers.Matchers.isType;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
 import com.google.errorprone.BugPattern;
@@ -18,7 +18,7 @@ import com.google.errorprone.util.ASTHelpers;
 import com.sun.source.tree.AnnotationTree;
 import com.sun.source.tree.ClassTree;
 import com.sun.source.tree.MethodTree;
-import com.sun.source.tree.Tree;
+import com.sun.source.tree.Tree.Kind;
 import com.sun.tools.javac.code.Symbol;
 import java.util.Map;
 import javax.lang.model.element.AnnotationValue;
@@ -46,7 +46,7 @@ public final class AmbiguousJsonCreator extends BugChecker implements Annotation
     }
 
     ClassTree clazz = state.findEnclosing(ClassTree.class);
-    if (clazz == null || clazz.getKind() != Tree.Kind.ENUM) {
+    if (clazz == null || clazz.getKind() != Kind.ENUM) {
       return Description.NO_MATCH;
     }
 

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

@@ -8,7 +8,7 @@ import static com.google.errorprone.matchers.Matchers.argument;
 import static com.google.errorprone.matchers.Matchers.argumentCount;
 import static com.google.errorprone.matchers.Matchers.instanceMethod;
 import static com.google.errorprone.matchers.Matchers.nullLiteral;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
 import com.google.errorprone.BugPattern;

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

@@ -6,7 +6,7 @@ import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
 import static com.google.errorprone.matchers.ChildMultiMatcher.MatchType.AT_LEAST_ONE;
 import static com.google.errorprone.matchers.Matchers.annotations;
 import static com.google.errorprone.matchers.Matchers.isType;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
 import com.google.common.collect.Iterables;
@@ -23,7 +23,7 @@ import com.sun.source.tree.ClassTree;
 import com.sun.source.tree.MethodTree;
 import com.sun.source.tree.Tree;
 import java.util.List;
-import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+import tech.picnic.errorprone.utils.SourceCode;
 
 /** A {@link BugChecker} that flags redundant {@code @Autowired} constructor annotations. */
 @AutoService(BugChecker.class)

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

@@ -3,7 +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 tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
 import com.google.common.collect.ImmutableSet;
@@ -19,14 +19,13 @@ 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 com.sun.source.tree.Tree.Kind;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
 import java.util.function.BiFunction;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
-import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+import tech.picnic.errorprone.utils.SourceCode;
 
 /** A {@link BugChecker} that flags annotations that could be written more concisely. */
 @AutoService(BugChecker.class)
@@ -119,7 +118,7 @@ public final class CanonicalAnnotationSyntax extends BugChecker implements Annot
        * the expression as a whole.
        */
       ExpressionTree value =
-          (arg.getKind() == Kind.ASSIGNMENT) ? ((AssignmentTree) arg).getExpression() : arg;
+          (arg instanceof AssignmentTree assignment) ? assignment.getExpression() : arg;
 
       /* Store a fix for each expression that was successfully simplified. */
       simplifyAttributeValue(value, state)
@@ -130,13 +129,10 @@ public final class CanonicalAnnotationSyntax extends BugChecker implements Annot
   }
 
   private static Optional<String> simplifyAttributeValue(ExpressionTree expr, VisitorState state) {
-    if (expr.getKind() != Kind.NEW_ARRAY) {
-      /* There are no curly braces or commas to be dropped here. */
-      return Optional.empty();
-    }
-
-    NewArrayTree array = (NewArrayTree) expr;
-    return simplifySingletonArray(array, state).or(() -> dropTrailingComma(array, state));
+    /* Drop curly braces or commas if possible. */
+    return expr instanceof NewArrayTree newArray
+        ? simplifySingletonArray(newArray, state).or(() -> dropTrailingComma(newArray, state))
+        : Optional.empty();
   }
 
   /** Returns the expression describing the array's sole element, if any. */

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

@@ -0,0 +1,91 @@
+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.FRAGILE_CODE;
+import static com.google.errorprone.matchers.Matchers.allOf;
+import static com.google.errorprone.matchers.Matchers.anything;
+import static com.google.errorprone.matchers.Matchers.classLiteral;
+import static com.google.errorprone.matchers.Matchers.instanceMethod;
+import static com.google.errorprone.matchers.Matchers.receiverOfInvocation;
+import static com.google.errorprone.matchers.Matchers.toType;
+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.annotations.Var;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
+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.BinaryTree;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.MethodInvocationTree;
+import com.sun.source.util.TreePath;
+import com.sun.tools.javac.code.Symbol.MethodSymbol;
+import java.util.regex.Pattern;
+
+/**
+ * A {@link BugChecker} that flags invocations of {@link Class#getName()} where {@link
+ * Class#getCanonicalName()} was likely meant.
+ *
+ * <p>For top-level types these two methods generally return the same result, but for nested types
+ * the former separates identifiers using a dollar sign ({@code $}) rather than a dot ({@code .}).
+ *
+ * @implNote This check currently only flags {@link Class#getName()} invocations on class literals,
+ *     and doesn't flag method references. This avoids false positives, such as suggesting use of
+ *     {@link Class#getCanonicalName()} in contexts where the canonical name is {@code null}.
+ */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "This code should likely use the type's canonical name",
+    link = BUG_PATTERNS_BASE_URL + "CanonicalClassNameUsage",
+    linkType = CUSTOM,
+    severity = WARNING,
+    tags = FRAGILE_CODE)
+public final class CanonicalClassNameUsage extends BugChecker
+    implements MethodInvocationTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Matcher<ExpressionTree> GET_NAME_INVOCATION =
+      toType(
+          MethodInvocationTree.class,
+          allOf(
+              receiverOfInvocation(classLiteral(anything())),
+              instanceMethod().onExactClass(Class.class.getCanonicalName()).named("getName")));
+  private static final Pattern CANONICAL_NAME_USING_TYPES =
+      Pattern.compile("(com\\.google\\.errorprone|tech\\.picnic\\.errorprone)\\..*");
+
+  /** Instantiates a new {@link CanonicalClassNameUsage} instance. */
+  public CanonicalClassNameUsage() {}
+
+  @Override
+  public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    if (!GET_NAME_INVOCATION.matches(tree, state) || !isPassedToCanonicalNameUsingType(state)) {
+      /*
+       * This is not a `class.getName()` invocation of which the result is passed to another method
+       * known to accept canonical type names.
+       */
+      return Description.NO_MATCH;
+    }
+
+    return describeMatch(
+        tree, SuggestedFixes.renameMethodInvocation(tree, "getCanonicalName", state));
+  }
+
+  private static boolean isPassedToCanonicalNameUsingType(VisitorState state) {
+    @Var TreePath path = state.getPath().getParentPath();
+    while (path.getLeaf() instanceof BinaryTree) {
+      path = path.getParentPath();
+    }
+
+    return path.getLeaf() instanceof MethodInvocationTree methodInvocation
+        && isOwnedByCanonicalNameUsingType(ASTHelpers.getSymbol(methodInvocation));
+  }
+
+  private static boolean isOwnedByCanonicalNameUsingType(MethodSymbol symbol) {
+    return CANONICAL_NAME_USING_TYPES.matcher(symbol.owner.getQualifiedName()).matches();
+  }
+}

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

@@ -0,0 +1,76 @@
+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 javax.lang.model.type.TypeKind;
+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()
+        || type.getKind() == TypeKind.TYPEVAR) {
+      /*
+       * The method reference syntax does not support casting to parameterized types, and type
+       * variables aren't supported either. 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/CollectorMutability.java

@@ -4,9 +4,12 @@ import static com.google.errorprone.BugPattern.LinkType.CUSTOM;
 import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
 import static com.google.errorprone.BugPattern.StandardTags.FRAGILE_CODE;
 import static com.google.errorprone.matchers.method.MethodMatchers.staticMethod;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
+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.VisitorState;
 import com.google.errorprone.bugpatterns.BugChecker;
@@ -17,8 +20,12 @@ import com.google.errorprone.matchers.Description;
 import com.google.errorprone.matchers.Matcher;
 import com.sun.source.tree.ExpressionTree;
 import com.sun.source.tree.MethodInvocationTree;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
 import java.util.stream.Collector;
-import tech.picnic.errorprone.bugpatterns.util.ThirdPartyLibrary;
+import java.util.stream.Collectors;
+import tech.picnic.errorprone.utils.ThirdPartyLibrary;
 
 /**
  * A {@link BugChecker} that flags {@link Collector Collectors} that don't clearly express
@@ -38,7 +45,7 @@ import tech.picnic.errorprone.bugpatterns.util.ThirdPartyLibrary;
 public final class CollectorMutability extends BugChecker implements MethodInvocationTreeMatcher {
   private static final long serialVersionUID = 1L;
   private static final Matcher<ExpressionTree> COLLECTOR_METHOD =
-      staticMethod().onClass("java.util.stream.Collectors");
+      staticMethod().onClass(Collectors.class.getCanonicalName());
   private static final Matcher<ExpressionTree> LIST_COLLECTOR =
       staticMethod().anyClass().named("toList");
   private static final Matcher<ExpressionTree> MAP_COLLECTOR =
@@ -58,7 +65,10 @@ public final class CollectorMutability extends BugChecker implements MethodInvoc
 
     if (LIST_COLLECTOR.matches(tree, state)) {
       return suggestToCollectionAlternatives(
-          tree, "com.google.common.collect.ImmutableList.toImmutableList", "ArrayList", state);
+          tree,
+          ImmutableList.class.getCanonicalName() + ".toImmutableList",
+          ArrayList.class.getCanonicalName(),
+          state);
     }
 
     if (MAP_COLLECTOR.matches(tree, state)) {
@@ -67,7 +77,10 @@ public final class CollectorMutability extends BugChecker implements MethodInvoc
 
     if (SET_COLLECTOR.matches(tree, state)) {
       return suggestToCollectionAlternatives(
-          tree, "com.google.common.collect.ImmutableSet.toImmutableSet", "HashSet", state);
+          tree,
+          ImmutableSet.class.getCanonicalName() + ".toImmutableSet",
+          HashSet.class.getCanonicalName(),
+          state);
     }
 
     return Description.NO_MATCH;
@@ -75,20 +88,20 @@ public final class CollectorMutability extends BugChecker implements MethodInvoc
 
   private Description suggestToCollectionAlternatives(
       MethodInvocationTree tree,
-      String fullyQualifiedImmutableReplacement,
+      String immutableReplacement,
       String mutableReplacement,
       VisitorState state) {
     SuggestedFix.Builder mutableFix = SuggestedFix.builder();
     String toCollectionSelect =
         SuggestedFixes.qualifyStaticImport(
-            "java.util.stream.Collectors.toCollection", mutableFix, state);
+            Collectors.class.getCanonicalName() + ".toCollection", mutableFix, state);
+    String mutableCollection = SuggestedFixes.qualifyType(state, mutableFix, mutableReplacement);
 
     return buildDescription(tree)
-        .addFix(replaceMethodInvocation(tree, fullyQualifiedImmutableReplacement, state))
+        .addFix(replaceMethodInvocation(tree, immutableReplacement, state))
         .addFix(
             mutableFix
-                .addImport(String.format("java.util.%s", mutableReplacement))
-                .replace(tree, String.format("%s(%s::new)", toCollectionSelect, mutableReplacement))
+                .replace(tree, String.format("%s(%s::new)", toCollectionSelect, mutableCollection))
                 .build())
         .build();
   }
@@ -99,17 +112,20 @@ public final class CollectorMutability extends BugChecker implements MethodInvoc
       return Description.NO_MATCH;
     }
 
+    SuggestedFix.Builder mutableFix = SuggestedFix.builder();
+    String hashMap =
+        SuggestedFixes.qualifyType(state, mutableFix, HashMap.class.getCanonicalName());
+
     return buildDescription(tree)
         .addFix(
             replaceMethodInvocation(
-                tree, "com.google.common.collect.ImmutableMap.toImmutableMap", state))
+                tree, ImmutableMap.class.getCanonicalName() + ".toImmutableMap", state))
         .addFix(
-            SuggestedFix.builder()
-                .addImport("java.util.HashMap")
+            mutableFix
                 .postfixWith(
                     tree.getArguments().get(argCount - 1),
                     (argCount == 2 ? ", (a, b) -> { throw new IllegalStateException(); }" : "")
-                        + ", HashMap::new")
+                        + String.format(", %s::new", hashMap))
                 .build())
         .build();
   }

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/DirectReturn.java

@@ -11,7 +11,7 @@ import static com.google.errorprone.matchers.Matchers.not;
 import static com.google.errorprone.matchers.Matchers.returnStatement;
 import static com.google.errorprone.matchers.Matchers.staticMethod;
 import static com.google.errorprone.matchers.Matchers.toType;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
 import com.google.common.collect.Streams;
@@ -39,8 +39,8 @@ import com.sun.tools.javac.code.Symbol;
 import java.util.List;
 import java.util.Optional;
 import org.jspecify.annotations.Nullable;
-import tech.picnic.errorprone.bugpatterns.util.MoreASTHelpers;
-import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+import tech.picnic.errorprone.utils.MoreASTHelpers;
+import tech.picnic.errorprone.utils.SourceCode;
 
 /**
  * A {@link BugChecker} that flags unnecessary local variable assignments preceding a return
@@ -58,7 +58,10 @@ public final class DirectReturn extends BugChecker implements BlockTreeMatcher {
   private static final Matcher<StatementTree> VARIABLE_RETURN = returnStatement(isVariable());
   private static final Matcher<ExpressionTree> MOCKITO_MOCK_OR_SPY_WITH_IMPLICIT_TYPE =
       allOf(
-          not(toType(MethodInvocationTree.class, argument(0, isSameType(Class.class.getName())))),
+          not(
+              toType(
+                  MethodInvocationTree.class,
+                  argument(0, isSameType(Class.class.getCanonicalName())))),
           staticMethod().onClass("org.mockito.Mockito").namedAnyOf("mock", "spy"));
 
   /** Instantiates a new {@link DirectReturn} instance. */
@@ -98,19 +101,17 @@ public final class DirectReturn extends BugChecker implements BlockTreeMatcher {
   }
 
   private static Optional<ExpressionTree> tryMatchAssignment(Symbol targetSymbol, Tree tree) {
-    if (tree instanceof ExpressionStatementTree) {
-      return tryMatchAssignment(targetSymbol, ((ExpressionStatementTree) tree).getExpression());
+    if (tree instanceof ExpressionStatementTree expressionStatement) {
+      return tryMatchAssignment(targetSymbol, expressionStatement.getExpression());
     }
 
-    if (tree instanceof AssignmentTree) {
-      AssignmentTree assignment = (AssignmentTree) tree;
+    if (tree instanceof AssignmentTree assignment) {
       return targetSymbol.equals(ASTHelpers.getSymbol(assignment.getVariable()))
           ? Optional.of(assignment.getExpression())
           : Optional.empty();
     }
 
-    if (tree instanceof VariableTree) {
-      VariableTree declaration = (VariableTree) tree;
+    if (tree instanceof VariableTree declaration) {
       return declaration.getModifiers().getAnnotations().isEmpty()
               && targetSymbol.equals(ASTHelpers.getSymbol(declaration))
           ? Optional.ofNullable(declaration.getInitializer())
@@ -148,11 +149,11 @@ public final class DirectReturn extends BugChecker implements BlockTreeMatcher {
             Streams.stream(state.getPath()).skip(1),
             Streams.stream(state.getPath()),
             (tree, child) -> {
-              if (!(tree instanceof TryTree)) {
+              if (!(tree instanceof TryTree tryTree)) {
                 return null;
               }
 
-              BlockTree finallyBlock = ((TryTree) tree).getFinallyBlock();
+              BlockTree finallyBlock = tryTree.getFinallyBlock();
               return !child.equals(finallyBlock) ? finallyBlock : null;
             })
         .anyMatch(finallyBlock -> referencesIdentifierSymbol(symbol, finallyBlock));

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

@@ -0,0 +1,325 @@
+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.PERFORMANCE;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+import static com.google.errorprone.matchers.Matchers.anyOf;
+import static com.google.errorprone.matchers.Matchers.isSubtypeOf;
+import static com.google.errorprone.matchers.Matchers.staticMethod;
+import static com.google.errorprone.matchers.method.MethodMatchers.instanceMethod;
+import static java.util.Objects.requireNonNull;
+import static java.util.stream.Collectors.joining;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
+
+import com.google.auto.service.AutoService;
+import com.google.auto.value.AutoValue;
+import com.google.common.base.Preconditions;
+import com.google.common.base.Verify;
+import com.google.common.base.VerifyException;
+import com.google.common.collect.ImmutableList;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.annotations.Var;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.google.errorprone.util.ASTHelpers;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.MethodInvocationTree;
+import com.sun.source.tree.Tree;
+import com.sun.tools.javac.code.Symbol;
+import com.sun.tools.javac.code.Symbol.MethodSymbol;
+import com.sun.tools.javac.code.Symbol.VarSymbol;
+import java.util.Collections;
+import java.util.Formattable;
+import java.util.List;
+import java.util.Locale;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.stream.Stream;
+import tech.picnic.errorprone.utils.SourceCode;
+
+/**
+ * A {@link BugChecker} that flags {@link String#format} and {@link String#formatted} invocations
+ * that can be omitted by delegating to another format method.
+ */
+// XXX: The special-casing of Throwable applies only to SLF4J 1.6.0+; see
+// https://www.slf4j.org/faq.html#paramException. That should be documented.
+// XXX: Some of the `Matcher`s defined here are also declared by the `Slf4jLogStatement` and
+// `RedundantStringConversion` checks. Look into deduplicating them.
+// XXX: Should we also simplify e.g. `LOG.error(String.join("sep", arg1, arg2), throwable)`? Perhaps
+// that's too obscure.
+// XXX: This check currently only flags string format expressions that are a direct argument to
+// another format-capable method invocation. Indirect cases, such as where the result is assigned to
+// a variable, are currently not covered.
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "String formatting can be deferred",
+    link = BUG_PATTERNS_BASE_URL + "EagerStringFormatting",
+    linkType = CUSTOM,
+    severity = WARNING,
+    tags = {PERFORMANCE, SIMPLIFICATION})
+public final class EagerStringFormatting extends BugChecker implements MethodInvocationTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Matcher<ExpressionTree> FORMATTABLE = isSubtypeOf(Formattable.class);
+  private static final Matcher<ExpressionTree> LOCALE = isSubtypeOf(Locale.class);
+  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> REQUIRE_NON_NULL_INVOCATION =
+      staticMethod().onClass(Objects.class.getCanonicalName()).named("requireNonNull");
+  private static final Matcher<ExpressionTree> GUAVA_GUARD_INVOCATION =
+      anyOf(
+          staticMethod()
+              .onClass(Preconditions.class.getCanonicalName())
+              .namedAnyOf("checkArgument", "checkNotNull", "checkState"),
+          staticMethod()
+              .onClass(Verify.class.getCanonicalName())
+              .namedAnyOf("verify", "verifyNotNull"));
+  private static final Matcher<ExpressionTree> SLF4J_LOGGER_INVOCATION =
+      instanceMethod()
+          .onDescendantOf("org.slf4j.Logger")
+          .namedAnyOf("trace", "debug", "info", "warn", "error");
+  private static final Matcher<ExpressionTree> STATIC_FORMAT_STRING =
+      staticMethod().onClass(String.class.getCanonicalName()).named("format");
+  private static final Matcher<ExpressionTree> INSTANCE_FORMAT_STRING =
+      instanceMethod().onDescendantOf(String.class.getCanonicalName()).named("formatted");
+  private static final String MESSAGE_NEVER_NULL_ARGUMENT =
+      "String formatting never yields `null` expression";
+
+  /** Instantiates a new {@link EagerStringFormatting} instance. */
+  public EagerStringFormatting() {}
+
+  @Override
+  public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    Tree parent = state.getPath().getParentPath().getLeaf();
+    if (!(parent instanceof MethodInvocationTree methodInvocation)) {
+      /*
+       * Fast path: this isn't a method invocation whose result is an argument to another method
+       * invocation.
+       */
+      // XXX: This logic assumes that the string format operation isn't redundantly wrapped in
+      // parentheses. Similar assumptions likely exist throughout the code base. Investigate how to
+      // structurally cover such cases.
+      return Description.NO_MATCH;
+    }
+
+    return StringFormatExpression.tryCreate(tree, state)
+        .map(expr -> analyzeFormatStringContext(expr, methodInvocation, state))
+        .orElse(Description.NO_MATCH);
+  }
+
+  private Description analyzeFormatStringContext(
+      StringFormatExpression stringFormat, MethodInvocationTree context, VisitorState state) {
+    if (REQUIRE_NON_NULL_INVOCATION.matches(context, state)) {
+      return analyzeRequireNonNullStringFormatContext(stringFormat, context);
+    }
+
+    if (GUAVA_GUARD_INVOCATION.matches(context, state)) {
+      return analyzeGuavaGuardStringFormatContext(stringFormat, context, state);
+    }
+
+    if (SLF4J_LOGGER_INVOCATION.matches(context, state)) {
+      return analyzeSlf4jLoggerStringFormatContext(stringFormat, context, state);
+    }
+
+    /*
+     * The string formatting operation does not appear to happen in a context that admits of
+     * simplification or optimization.
+     */
+    return Description.NO_MATCH;
+  }
+
+  private Description analyzeRequireNonNullStringFormatContext(
+      StringFormatExpression stringFormat, MethodInvocationTree context) {
+    List<? extends ExpressionTree> arguments = context.getArguments();
+    if (arguments.size() != 2 || arguments.get(0).equals(stringFormat.expression())) {
+      /* Vacuous validation that string formatting doesn't yield `null`. */
+      return buildDescription(context).setMessage(MESSAGE_NEVER_NULL_ARGUMENT).build();
+    }
+
+    if (stringFormat.arguments().stream()
+        .anyMatch(EagerStringFormatting::isNonFinalLocalVariable)) {
+      /*
+       * The format operation depends on a variable that isn't final or effectively final; moving
+       * it into a lambda expression would cause a compilation error.
+       */
+      return buildDescription(context)
+          .setMessage(message() + " (but this requires introducing an effectively final variable)")
+          .build();
+    }
+
+    /* Suggest that the string formatting is deferred. */
+    return describeMatch(context, SuggestedFix.prefixWith(stringFormat.expression(), "() -> "));
+  }
+
+  private Description analyzeGuavaGuardStringFormatContext(
+      StringFormatExpression stringFormat, MethodInvocationTree context, VisitorState state) {
+    List<? extends ExpressionTree> arguments = context.getArguments();
+    if (arguments.get(0).equals(stringFormat.expression())) {
+      /*
+       * Vacuous `checkNotNull` or `verifyNotNull` validation that string formatting doesn't yield
+       * `null`.
+       */
+      return buildDescription(context).setMessage(MESSAGE_NEVER_NULL_ARGUMENT).build();
+    }
+
+    if (stringFormat.simplifiableFormatString().isEmpty() || arguments.size() > 2) {
+      /*
+       * The format string cannot be simplified, or the format string produces a format string
+       * itself, or its result is the input to another format operation. These are complex cases
+       * that we'll only flag.
+       */
+      return createSimplificationSuggestion(context, "Guava");
+    }
+
+    return describeMatch(context, stringFormat.suggestFlattening("%s", state));
+  }
+
+  private Description analyzeSlf4jLoggerStringFormatContext(
+      StringFormatExpression stringFormat, MethodInvocationTree context, VisitorState state) {
+    if (stringFormat.simplifiableFormatString().isEmpty()) {
+      /* We can't simplify this case; only flag it. */
+      return createSimplificationSuggestion(context, "SLF4J");
+    }
+
+    List<? extends ExpressionTree> arguments = context.getArguments();
+    int leftOffset = SLF4J_MARKER.matches(arguments.get(0), state) ? 1 : 0;
+    int rightOffset = THROWABLE.matches(arguments.get(arguments.size() - 1), state) ? 1 : 0;
+    if (arguments.size() != leftOffset + 1 + rightOffset) {
+      /*
+       * The format string produces a format string itself, or its result is the input to another
+       * format operation. This is a complex case that we'll only flag.
+       */
+      return createSimplificationSuggestion(context, "SLF4J");
+    }
+
+    return describeMatch(context, stringFormat.suggestFlattening("{}", state));
+  }
+
+  private static boolean isNonFinalLocalVariable(Tree tree) {
+    Symbol symbol = ASTHelpers.getSymbol(tree);
+    return symbol instanceof VarSymbol
+        && symbol.owner instanceof MethodSymbol
+        && !ASTHelpers.isConsideredFinal(symbol);
+  }
+
+  private Description createSimplificationSuggestion(MethodInvocationTree context, String library) {
+    return buildDescription(context)
+        .setMessage(
+            "%s (assuming that %s's simplified formatting support suffices)"
+                .formatted(message(), library))
+        .build();
+  }
+
+  /** Description of a string format expression. */
+  @AutoValue
+  abstract static class StringFormatExpression {
+    /** The full string format expression. */
+    abstract MethodInvocationTree expression();
+
+    /** The format string expression. */
+    abstract Tree formatString();
+
+    /** The string format arguments to be plugged into its format string. */
+    abstract ImmutableList<ExpressionTree> arguments();
+
+    /**
+     * The constant format string, if it contains only {@code %s} placeholders, and the number of
+     * said placeholders matches the number of format arguments.
+     */
+    abstract Optional<String> simplifiableFormatString();
+
+    private SuggestedFix suggestFlattening(String newPlaceholder, VisitorState state) {
+      return SuggestedFix.replace(
+          expression(),
+          Stream.concat(
+                  Stream.of(deriveFormatStringExpression(newPlaceholder, state)),
+                  arguments().stream().map(arg -> SourceCode.treeToString(arg, state)))
+              .collect(joining(", ")));
+    }
+
+    private String deriveFormatStringExpression(String newPlaceholder, VisitorState state) {
+      String formatString =
+          String.format(
+              simplifiableFormatString()
+                  .orElseThrow(() -> new VerifyException("Format string cannot be simplified")),
+              Collections.nCopies(arguments().size(), newPlaceholder).toArray());
+
+      /*
+       * If the suggested replacement format string is the same as the original, then use the
+       * expression's existing source code representation. This way string constant references are
+       * not unnecessarily replaced.
+       */
+      return formatString.equals(ASTHelpers.constValue(formatString(), String.class))
+          ? SourceCode.treeToString(formatString(), state)
+          : SourceCode.toStringConstantExpression(formatString, state);
+    }
+
+    private static Optional<StringFormatExpression> tryCreate(
+        MethodInvocationTree tree, VisitorState state) {
+      if (INSTANCE_FORMAT_STRING.matches(tree, state)) {
+        return Optional.of(
+            create(
+                tree,
+                requireNonNull(ASTHelpers.getReceiver(tree), "Receiver unexpectedly absent"),
+                ImmutableList.copyOf(tree.getArguments()),
+                state));
+      }
+
+      if (STATIC_FORMAT_STRING.matches(tree, state)) {
+        List<? extends ExpressionTree> arguments = tree.getArguments();
+        int argOffset = LOCALE.matches(arguments.get(0), state) ? 1 : 0;
+        return Optional.of(
+            create(
+                tree,
+                arguments.get(argOffset),
+                ImmutableList.copyOf(arguments.subList(argOffset + 1, arguments.size())),
+                state));
+      }
+
+      return Optional.empty();
+    }
+
+    private static StringFormatExpression create(
+        MethodInvocationTree expression,
+        Tree formatString,
+        ImmutableList<ExpressionTree> arguments,
+        VisitorState state) {
+      return new AutoValue_EagerStringFormatting_StringFormatExpression(
+          expression,
+          formatString,
+          arguments,
+          Optional.ofNullable(ASTHelpers.constValue(formatString, String.class))
+              .filter(template -> isSimplifiable(template, arguments, state)));
+    }
+
+    private static boolean isSimplifiable(
+        String formatString, ImmutableList<ExpressionTree> arguments, VisitorState state) {
+      if (arguments.stream().anyMatch(arg -> FORMATTABLE.matches(arg, state))) {
+        /* `Formattable` arguments can have arbitrary format semantics. */
+        return false;
+      }
+
+      @Var int placeholderCount = 0;
+      for (int p = formatString.indexOf('%'); p != -1; p = formatString.indexOf('%', p + 2)) {
+        if (p == formatString.length() - 1) {
+          /* Malformed format string with trailing `%`. */
+          return false;
+        }
+
+        char modifier = formatString.charAt(p + 1);
+        if (modifier == 's') {
+          placeholderCount++;
+        } else if (modifier != '%') {
+          /* Only `%s` and `%%` (a literal `%`) are supported. */
+          return false;
+        }
+      }
+
+      return placeholderCount == arguments.size();
+    }
+  }
+}

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

@@ -7,7 +7,7 @@ import static com.google.errorprone.matchers.ChildMultiMatcher.MatchType.AT_LEAS
 import static com.google.errorprone.matchers.Matchers.annotations;
 import static com.google.errorprone.matchers.Matchers.anyOf;
 import static com.google.errorprone.matchers.Matchers.isType;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
 import com.google.errorprone.BugPattern;
@@ -21,7 +21,7 @@ import com.sun.source.tree.ClassTree;
 import com.sun.source.tree.MethodTree;
 import com.sun.source.tree.Tree;
 import java.util.Optional;
-import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+import tech.picnic.errorprone.utils.SourceCode;
 
 /** A {@link BugChecker} that flags empty methods that seemingly can simply be deleted. */
 @AutoService(BugChecker.class)
@@ -36,7 +36,9 @@ public final class EmptyMethod extends BugChecker implements MethodTreeMatcher {
   private static final Matcher<Tree> PERMITTED_ANNOTATION =
       annotations(
           AT_LEAST_ONE,
-          anyOf(isType("java.lang.Override"), isType("org.aspectj.lang.annotation.Pointcut")));
+          anyOf(
+              isType(Override.class.getCanonicalName()),
+              isType("org.aspectj.lang.annotation.Pointcut")));
 
   /** Instantiates a new {@link EmptyMethod} instance. */
   public EmptyMethod() {}
@@ -60,7 +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/EmptyMonoZip.java

@@ -0,0 +1,89 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.CUSTOM;
+import static com.google.errorprone.BugPattern.SeverityLevel.ERROR;
+import static com.google.errorprone.BugPattern.StandardTags.LIKELY_ERROR;
+import static com.google.errorprone.matchers.Matchers.anyOf;
+import static com.google.errorprone.matchers.Matchers.instanceMethod;
+import static com.google.errorprone.matchers.Matchers.staticMethod;
+import static com.google.errorprone.matchers.Matchers.typePredicateMatcher;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.MoreTypePredicates.isSubTypeOf;
+import static tech.picnic.errorprone.utils.MoreTypes.generic;
+import static tech.picnic.errorprone.utils.MoreTypes.type;
+
+import com.google.auto.service.AutoService;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.google.errorprone.suppliers.Supplier;
+import com.google.errorprone.suppliers.Suppliers;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.MemberSelectTree;
+import com.sun.source.tree.MethodInvocationTree;
+import com.sun.tools.javac.code.Type;
+import reactor.core.publisher.Mono;
+
+/**
+ * A {@link BugChecker} that flags {@link Mono#zip} and {@link Mono#zipWith} invocations with a
+ * {@code Mono<Void>} or {@link Mono#empty()} argument or receiver.
+ *
+ * <p>When a zipped reactive stream completes empty, then the other zipped streams will be cancelled
+ * (or not subscribed to), and the operation as a whole will complete empty as well. This is
+ * generally not what was intended.
+ */
+// XXX: Generalize this check to also cover `Flux` zip operations.
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "Don't pass a `Mono<Void>` or `Mono.empty()` argument to `Mono#{zip,With}`",
+    link = BUG_PATTERNS_BASE_URL + "EmptyMonoZip",
+    linkType = CUSTOM,
+    severity = ERROR,
+    tags = LIKELY_ERROR)
+public final class EmptyMonoZip extends BugChecker implements MethodInvocationTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Supplier<Type> MONO =
+      Suppliers.typeFromString("reactor.core.publisher.Mono");
+  private static final Matcher<ExpressionTree> MONO_ZIP_OR_ZIP_WITH =
+      anyOf(
+          instanceMethod().onDescendantOf(MONO).named("zipWith"),
+          staticMethod().onClass(MONO).named("zip"));
+  private static final Matcher<ExpressionTree> EMPTY_MONO =
+      anyOf(
+          staticMethod().onDescendantOf(MONO).named("empty"),
+          typePredicateMatcher(isSubTypeOf(generic(MONO, type(Void.class.getCanonicalName())))));
+
+  /** Instantiates a new {@link EmptyMonoZip} instance. */
+  public EmptyMonoZip() {}
+
+  @Override
+  public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    if (!MONO_ZIP_OR_ZIP_WITH.matches(tree, state)) {
+      return Description.NO_MATCH;
+    }
+
+    if (hasEmptyReceiver(tree, state)) {
+      return buildDescription(tree)
+          .setMessage("Invoking `Mono#zipWith` on `Mono#empty()` or a `Mono<Void>` is a no-op")
+          .build();
+    }
+
+    if (hasEmptyArguments(tree, state)) {
+      return describeMatch(tree);
+    }
+
+    return Description.NO_MATCH;
+  }
+
+  private static boolean hasEmptyReceiver(MethodInvocationTree tree, VisitorState state) {
+    return tree.getMethodSelect() instanceof MemberSelectTree memberSelect
+        && EMPTY_MONO.matches(memberSelect.getExpression(), state);
+  }
+
+  private static boolean hasEmptyArguments(MethodInvocationTree tree, VisitorState state) {
+    return tree.getArguments().stream().anyMatch(arg -> EMPTY_MONO.matches(arg, state));
+  }
+}

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

@@ -0,0 +1,233 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.common.collect.ImmutableList.toImmutableList;
+import static com.google.errorprone.BugPattern.LinkType.CUSTOM;
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static com.google.errorprone.BugPattern.StandardTags.PERFORMANCE;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+import static com.google.errorprone.matchers.Matchers.allOf;
+import static com.google.errorprone.matchers.Matchers.anyOf;
+import static com.google.errorprone.matchers.Matchers.instanceMethod;
+import static com.google.errorprone.matchers.Matchers.staticMethod;
+import static com.google.errorprone.matchers.Matchers.symbolMatcher;
+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.ImmutableMultiset;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.ImmutableTable;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.fixes.SuggestedFixes;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.google.errorprone.util.ASTHelpers;
+import com.google.errorprone.util.Visibility;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.MethodInvocationTree;
+import com.sun.source.tree.MethodTree;
+import com.sun.tools.javac.code.Symbol.MethodSymbol;
+import com.sun.tools.javac.code.Symbol.VarSymbol;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.Set;
+import javax.lang.model.element.Element;
+import tech.picnic.errorprone.utils.SourceCode;
+
+/**
+ * A {@link BugChecker} that flags single-argument method invocations with an iterable of explicitly
+ * enumerated values, for which a semantically equivalent varargs variant (appears to) exists as
+ * well.
+ *
+ * <p>This check drops selected {@link ImmutableSet#of} and {@link Set#of} invocations, with the
+ * assumption that these operations do not deduplicate the collection of explicitly enumerated
+ * values. It also drops {@link ImmutableMultiset#of} and {@link Set#of} invocations, with the
+ * assumption that these do not materially impact iteration order.
+ *
+ * <p>This checker attempts to identify {@link Iterable}-accepting methods for which a varargs
+ * overload exists, and suggests calling the varargs overload instead. This is an imperfect
+ * heuristic, but it e.g. allows invocations of <a
+ * href="https://immutables.github.io/immutable.html#copy-methods">Immutables-generated {@code
+ * with*}</a> methods to be simplified.
+ */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "Iterable creation can be avoided by using a varargs alternative method",
+    link = BUG_PATTERNS_BASE_URL + "ExplicitArgumentEnumeration",
+    linkType = CUSTOM,
+    severity = SUGGESTION,
+    tags = {PERFORMANCE, SIMPLIFICATION})
+public final class ExplicitArgumentEnumeration extends BugChecker
+    implements MethodInvocationTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Matcher<ExpressionTree> EXPLICIT_ITERABLE_CREATOR =
+      anyOf(
+          staticMethod()
+              .onClassAny(
+                  ImmutableList.class.getCanonicalName(),
+                  ImmutableMultiset.class.getCanonicalName(),
+                  ImmutableSet.class.getCanonicalName(),
+                  List.class.getCanonicalName(),
+                  Set.class.getCanonicalName())
+              .named("of"),
+          allOf(
+              staticMethod()
+                  .onClassAny(
+                      ImmutableList.class.getCanonicalName(),
+                      ImmutableMultiset.class.getCanonicalName(),
+                      ImmutableSet.class.getCanonicalName())
+                  .named("copyOf"),
+              symbolMatcher(
+                  (symbol, state) ->
+                      state
+                          .getSymtab()
+                          .arrayClass
+                          .equals(((MethodSymbol) symbol).params().get(0).type.tsym))),
+          staticMethod().onClass(Arrays.class.getCanonicalName()).named("asList"));
+  private static final Matcher<ExpressionTree> IMMUTABLE_COLLECTION_BUILDER =
+      instanceMethod().onDescendantOf(ImmutableCollection.Builder.class.getCanonicalName());
+  private static final Matcher<ExpressionTree> OBJECT_ENUMERABLE_ASSERT =
+      instanceMethod().onDescendantOf("org.assertj.core.api.ObjectEnumerableAssert");
+  private static final Matcher<ExpressionTree> STEP_VERIFIER_STEP =
+      instanceMethod().onDescendantOf("reactor.test.StepVerifier.Step");
+  private static final ImmutableTable<Matcher<ExpressionTree>, String, String> ALTERNATIVE_METHODS =
+      ImmutableTable.<Matcher<ExpressionTree>, String, String>builder()
+          .put(IMMUTABLE_COLLECTION_BUILDER, "addAll", "add")
+          .put(OBJECT_ENUMERABLE_ASSERT, "containsAnyElementsOf", "containsAnyOf")
+          .put(OBJECT_ENUMERABLE_ASSERT, "containsAll", "contains")
+          .put(OBJECT_ENUMERABLE_ASSERT, "containsExactlyElementsOf", "containsExactly")
+          .put(
+              OBJECT_ENUMERABLE_ASSERT,
+              "containsExactlyInAnyOrderElementsOf",
+              "containsExactlyInAnyOrder")
+          .put(OBJECT_ENUMERABLE_ASSERT, "containsOnlyElementsOf", "containsOnly")
+          .put(OBJECT_ENUMERABLE_ASSERT, "containsOnlyOnceElementsOf", "containsOnlyOnce")
+          .put(OBJECT_ENUMERABLE_ASSERT, "doesNotContainAnyElementsOf", "doesNotContain")
+          .put(OBJECT_ENUMERABLE_ASSERT, "hasSameElementsAs", "containsOnly")
+          .put(STEP_VERIFIER_STEP, "expectNextSequence", "expectNext")
+          .buildOrThrow();
+
+  /** Instantiates a new {@link ExplicitArgumentEnumeration} instance. */
+  public ExplicitArgumentEnumeration() {}
+
+  @Override
+  public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    if (tree.getArguments().size() != 1) {
+      /* Performance optimization: non-unary method invocations cannot be simplified. */
+      return Description.NO_MATCH;
+    }
+
+    MethodSymbol method = ASTHelpers.getSymbol(tree);
+    if (!isUnaryIterableAcceptingMethod(method, state) || isLocalOverload(method, state)) {
+      /*
+       * This isn't a method invocation we can simplify, or it's an invocation of a local overload.
+       * The latter type of invocation we do not suggest replacing, as this is fairly likely to
+       * introduce an unbounded recursive call chain.
+       */
+      return Description.NO_MATCH;
+    }
+
+    ExpressionTree argument = tree.getArguments().get(0);
+    if (!EXPLICIT_ITERABLE_CREATOR.matches(argument, state)) {
+      return Description.NO_MATCH;
+    }
+
+    return trySuggestCallingVarargsOverload(method, (MethodInvocationTree) argument, state)
+        .or(() -> trySuggestCallingCustomAlternative(tree, (MethodInvocationTree) argument, state))
+        .map(fix -> describeMatch(tree, fix))
+        .orElse(Description.NO_MATCH);
+  }
+
+  private static boolean isUnaryIterableAcceptingMethod(MethodSymbol method, VisitorState state) {
+    List<VarSymbol> params = method.params();
+    return !method.isVarArgs()
+        && params.size() == 1
+        && ASTHelpers.isSubtype(params.get(0).type, state.getSymtab().iterableType, state);
+  }
+
+  private static boolean isLocalOverload(MethodSymbol calledMethod, VisitorState state) {
+    MethodTree enclosingMethod = state.findEnclosing(MethodTree.class);
+    if (enclosingMethod == null) {
+      return false;
+    }
+
+    MethodSymbol callingMethod = ASTHelpers.getSymbol(enclosingMethod);
+    return Objects.equals(callingMethod.getEnclosingElement(), calledMethod.getEnclosingElement())
+        && callingMethod.getSimpleName().equals(calledMethod.getSimpleName());
+  }
+
+  private static Optional<SuggestedFix> trySuggestCallingVarargsOverload(
+      MethodSymbol method, MethodInvocationTree argument, VisitorState state) {
+    /*
+     * Collect all overloads of the given method that we are sure to be able to call. Note that the
+     * `isAtLeastAsVisible` check is conservative heuristic.
+     */
+    ImmutableList<MethodSymbol> overloads =
+        ASTHelpers.matchingMethods(
+                method.getSimpleName(),
+                m -> isAtLeastAsVisible(m, method),
+                method.enclClass().type,
+                state.getTypes())
+            .collect(toImmutableList());
+
+    /*
+     * If all overloads have a single parameter, and at least one of them is a varargs method, then
+     * we assume that unwrapping the iterable argument will cause a suitable overload to be invoked.
+     * (Note that there may be multiple varargs overloads, either with different parameter types, or
+     * due to method overriding; this check does not attempt to determine which exact method or
+     * overload will be invoked as a result of the suggested simplification.)
+     *
+     * Note that this is a (highly!) imperfect heuristic, but it is sufficient to prevent e.g.
+     * unwrapping of arguments to `org.jooq.impl.DSL#row`, which can cause the expression's return
+     * type to change from `RowN` to (e.g.) `Row2`.
+     */
+    // XXX: There are certainly cases where it _would_ be nice to unwrap the arguments to
+    // `org.jooq.impl.DSL#row(Collection<?>)`. Look into this.
+    // XXX: Ideally we do check that one of the overloads accepts the unwrapped arguments.
+    // XXX: Ideally we validate that eligible overloads have compatible return types.
+    boolean hasLikelySuitableVarargsOverload =
+        overloads.stream().allMatch(m -> m.params().size() == 1)
+            && overloads.stream().anyMatch(MethodSymbol::isVarArgs);
+
+    return hasLikelySuitableVarargsOverload
+        ? Optional.of(SourceCode.unwrapMethodInvocation(argument, state))
+        : Optional.empty();
+  }
+
+  private static Optional<SuggestedFix> trySuggestCallingCustomAlternative(
+      MethodInvocationTree tree, MethodInvocationTree argument, VisitorState state) {
+    return ALTERNATIVE_METHODS.rowMap().entrySet().stream()
+        .filter(e -> e.getKey().matches(tree, state))
+        .findFirst()
+        .flatMap(e -> trySuggestCallingCustomAlternative(tree, argument, state, e.getValue()));
+  }
+
+  private static Optional<SuggestedFix> trySuggestCallingCustomAlternative(
+      MethodInvocationTree tree,
+      MethodInvocationTree argument,
+      VisitorState state,
+      Map<String, String> alternatives) {
+    return Optional.ofNullable(
+            alternatives.get(ASTHelpers.getSymbol(tree).getSimpleName().toString()))
+        .map(
+            replacement ->
+                SuggestedFix.builder()
+                    .merge(SuggestedFixes.renameMethodInvocation(tree, replacement, state))
+                    .merge(SourceCode.unwrapMethodInvocation(argument, state))
+                    .build());
+  }
+
+  private static boolean isAtLeastAsVisible(Element symbol, Element reference) {
+    return Visibility.fromModifiers(symbol.getModifiers())
+            .compareTo(Visibility.fromModifiers(reference.getModifiers()))
+        >= 0;
+  }
+}

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

@@ -7,7 +7,7 @@ import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
 import static com.google.errorprone.BugPattern.StandardTags.FRAGILE_CODE;
 import static com.google.errorprone.matchers.method.MethodMatchers.staticMethod;
 import static java.util.stream.Collectors.collectingAndThen;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
 import com.google.common.collect.ImmutableSet;
@@ -44,7 +44,7 @@ import java.util.stream.Stream;
 public final class ExplicitEnumOrdering extends BugChecker implements MethodInvocationTreeMatcher {
   private static final long serialVersionUID = 1L;
   private static final Matcher<ExpressionTree> EXPLICIT_ORDERING =
-      staticMethod().onClass(Ordering.class.getName()).named("explicit");
+      staticMethod().onClass(Ordering.class.getCanonicalName()).named("explicit");
 
   /** Instantiates a new {@link ExplicitEnumOrdering} instance. */
   public ExplicitEnumOrdering() {}
@@ -72,7 +72,7 @@ public final class ExplicitEnumOrdering extends BugChecker implements MethodInvo
       List<? extends ExpressionTree> expressions) {
     return expressions.stream()
         .map(ASTHelpers::getSymbol)
-        .filter(Symbol::isEnum)
+        .filter(s -> s != null && s.isEnum())
         .collect(
             collectingAndThen(
                 toImmutableSetMultimap(Symbol::asType, Symbol::toString),

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

@@ -4,11 +4,11 @@ import static com.google.errorprone.BugPattern.LinkType.CUSTOM;
 import static com.google.errorprone.BugPattern.SeverityLevel.ERROR;
 import static com.google.errorprone.BugPattern.StandardTags.LIKELY_ERROR;
 import static com.google.errorprone.matchers.method.MethodMatchers.instanceMethod;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
-import static tech.picnic.errorprone.bugpatterns.util.MoreTypes.generic;
-import static tech.picnic.errorprone.bugpatterns.util.MoreTypes.subOf;
-import static tech.picnic.errorprone.bugpatterns.util.MoreTypes.type;
-import static tech.picnic.errorprone.bugpatterns.util.MoreTypes.unbound;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.MoreTypes.generic;
+import static tech.picnic.errorprone.utils.MoreTypes.subOf;
+import static tech.picnic.errorprone.utils.MoreTypes.type;
+import static tech.picnic.errorprone.utils.MoreTypes.unbound;
 
 import com.google.auto.service.AutoService;
 import com.google.common.collect.Iterables;
@@ -50,8 +50,9 @@ import reactor.core.publisher.Flux;
 @AutoService(BugChecker.class)
 @BugPattern(
     summary =
-        "`Flux#flatMap` and `Flux#flatMapSequential` have subtle semantics; "
-            + "please use `Flux#concatMap` or explicitly specify the desired amount of concurrency",
+        """
+        `Flux#flatMap` and `Flux#flatMapSequential` have subtle semantics; please use \
+        `Flux#concatMap` or explicitly specify the desired amount of concurrency""",
     link = BUG_PATTERNS_BASE_URL + "FluxFlatMapUsage",
     linkType = CUSTOM,
     severity = ERROR,
@@ -66,7 +67,7 @@ public final class FluxFlatMapUsage extends BugChecker
       instanceMethod()
           .onDescendantOf(FLUX)
           .namedAnyOf("flatMap", "flatMapSequential")
-          .withParameters(Function.class.getName());
+          .withParameters(Function.class.getCanonicalName());
   private static final Supplier<Type> FLUX_OF_PUBLISHERS =
       VisitorState.memoize(
           generic(FLUX, subOf(generic(type("org.reactivestreams.Publisher"), unbound()))));

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

@@ -6,9 +6,10 @@ import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
 import static com.google.errorprone.BugPattern.StandardTags.CONCURRENCY;
 import static com.google.errorprone.BugPattern.StandardTags.PERFORMANCE;
 import static com.google.errorprone.matchers.method.MethodMatchers.instanceMethod;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
+import com.google.common.collect.ImmutableList;
 import com.google.errorprone.BugPattern;
 import com.google.errorprone.VisitorState;
 import com.google.errorprone.bugpatterns.BugChecker;
@@ -24,8 +25,9 @@ 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.Position;
+import java.util.stream.Collectors;
 import java.util.stream.Stream;
-import tech.picnic.errorprone.bugpatterns.util.ThirdPartyLibrary;
+import tech.picnic.errorprone.utils.ThirdPartyLibrary;
 
 /**
  * A {@link BugChecker} that flags {@link reactor.core.publisher.Flux} operator usages that may
@@ -48,7 +50,8 @@ public final class FluxImplicitBlock extends BugChecker implements MethodInvocat
           .onDescendantOf("reactor.core.publisher.Flux")
           .namedAnyOf("toIterable", "toStream")
           .withNoParameters();
-  private static final Supplier<Type> STREAM = Suppliers.typeFromString(Stream.class.getName());
+  private static final Supplier<Type> STREAM =
+      Suppliers.typeFromString(Stream.class.getCanonicalName());
 
   /** Instantiates a new {@link FluxImplicitBlock} instance. */
   public FluxImplicitBlock() {}
@@ -64,10 +67,11 @@ public final class FluxImplicitBlock extends BugChecker implements MethodInvocat
     if (ThirdPartyLibrary.GUAVA.isIntroductionAllowed(state)) {
       description.addFix(
           suggestBlockingElementCollection(
-              tree, "com.google.common.collect.ImmutableList.toImmutableList", state));
+              tree, ImmutableList.class.getCanonicalName() + ".toImmutableList", state));
     }
     description.addFix(
-        suggestBlockingElementCollection(tree, "java.util.stream.Collectors.toList", state));
+        suggestBlockingElementCollection(
+            tree, Collectors.class.getCanonicalName() + ".toList", state));
 
     return description.build();
   }

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

@@ -10,9 +10,11 @@ import static com.google.errorprone.matchers.Matchers.instanceMethod;
 import static com.google.errorprone.matchers.Matchers.not;
 import static com.google.errorprone.matchers.Matchers.staticMethod;
 import static java.util.stream.Collectors.joining;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
+import com.google.common.base.Preconditions;
+import com.google.common.base.Verify;
 import com.google.errorprone.BugPattern;
 import com.google.errorprone.VisitorState;
 import com.google.errorprone.bugpatterns.BugChecker;
@@ -30,10 +32,12 @@ import com.sun.source.tree.Tree;
 import com.sun.source.tree.Tree.Kind;
 import com.sun.source.util.SimpleTreeVisitor;
 import java.util.ArrayList;
+import java.util.Formatter;
 import java.util.List;
 import java.util.Optional;
 import org.jspecify.annotations.Nullable;
-import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+import tech.picnic.errorprone.utils.MoreASTHelpers;
+import tech.picnic.errorprone.utils.SourceCode;
 
 /**
  * A {@link BugChecker} that flags string concatenations that produce a format string; in such cases
@@ -68,7 +72,7 @@ public final class FormatStringConcatenation extends BugChecker
       anyMethod()
           .anyClass()
           .withAnyName()
-          .withParameters(String.class.getName(), Throwable.class.getName());
+          .withParameters(String.class.getCanonicalName(), Throwable.class.getCanonicalName());
 
   // XXX: Drop some of these methods if we use Refaster to replace some with others.
   private static final Matcher<ExpressionTree> ASSERTJ_FORMAT_METHOD =
@@ -118,14 +122,14 @@ public final class FormatStringConcatenation extends BugChecker
   private static final Matcher<ExpressionTree> GUAVA_FORMAT_METHOD =
       anyOf(
           staticMethod()
-              .onClass("com.google.common.base.Preconditions")
+              .onClass(Preconditions.class.getCanonicalName())
               .namedAnyOf("checkArgument", "checkNotNull", "checkState"),
-          staticMethod().onClass("com.google.common.base.Verify").named("verify"));
+          staticMethod().onClass(Verify.class.getCanonicalName()).named("verify"));
   // XXX: Add `PrintWriter`, maybe others.
   private static final Matcher<ExpressionTree> JDK_FORMAT_METHOD =
       anyOf(
-          staticMethod().onClass("java.lang.String").named("format"),
-          instanceMethod().onExactClass("java.util.Formatter").named("format"));
+          staticMethod().onClass(String.class.getCanonicalName()).named("format"),
+          instanceMethod().onExactClass(Formatter.class.getCanonicalName()).named("format"));
   private static final Matcher<ExpressionTree> SLF4J_FORMAT_METHOD =
       instanceMethod()
           .onDescendantOf("org.slf4j.Logger")
@@ -200,14 +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();
@@ -220,7 +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 {
@@ -242,8 +242,8 @@ public final class FormatStringConcatenation extends BugChecker
     }
 
     private void appendExpression(Tree tree) {
-      if (tree instanceof LiteralTree) {
-        formatString.append(((LiteralTree) tree).getValue());
+      if (tree instanceof LiteralTree literal) {
+        formatString.append(literal.getValue());
       } else {
         formatString.append(formatSpecifier);
         formatArguments.add(tree);

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

@@ -7,9 +7,20 @@ import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
 import static com.google.errorprone.matchers.Matchers.anyOf;
 import static com.google.errorprone.matchers.Matchers.staticMethod;
 import static com.google.errorprone.suppliers.Suppliers.OBJECT_TYPE;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
+import com.google.common.collect.ImmutableBiMap;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableListMultimap;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableMultimap;
+import com.google.common.collect.ImmutableMultiset;
+import com.google.common.collect.ImmutableRangeMap;
+import com.google.common.collect.ImmutableRangeSet;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.ImmutableSetMultimap;
+import com.google.common.collect.ImmutableTable;
 import com.google.common.primitives.Primitives;
 import com.google.errorprone.BugPattern;
 import com.google.errorprone.VisitorState;
@@ -20,6 +31,7 @@ import com.google.errorprone.fixes.SuggestedFix;
 import com.google.errorprone.fixes.SuggestedFixes;
 import com.google.errorprone.matchers.Description;
 import com.google.errorprone.matchers.Matcher;
+import com.google.errorprone.matchers.Matchers;
 import com.google.errorprone.util.ASTHelpers;
 import com.google.errorprone.util.ASTHelpers.TargetType;
 import com.sun.source.tree.ExpressionTree;
@@ -27,9 +39,10 @@ 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.bugpatterns.util.SourceCode;
+import tech.picnic.errorprone.utils.SourceCode;
 
 /** A {@link BugChecker} that flags redundant identity conversions. */
 // XXX: Consider detecting cases where a flagged expression is passed to a method, and where removal
@@ -39,6 +52,7 @@ import tech.picnic.errorprone.bugpatterns.util.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",
@@ -56,24 +70,23 @@ public final class IdentityConversion extends BugChecker implements MethodInvoca
                       .map(Class::getName)
                       .collect(toImmutableSet()))
               .named("valueOf"),
-          staticMethod().onClass(String.class.getName()).named("valueOf"),
+          staticMethod().onClass(String.class.getCanonicalName()).named("valueOf"),
           staticMethod()
               .onClassAny(
-                  "com.google.common.collect.ImmutableBiMap",
-                  "com.google.common.collect.ImmutableList",
-                  "com.google.common.collect.ImmutableListMultimap",
-                  "com.google.common.collect.ImmutableMap",
-                  "com.google.common.collect.ImmutableMultimap",
-                  "com.google.common.collect.ImmutableMultiset",
-                  "com.google.common.collect.ImmutableRangeMap",
-                  "com.google.common.collect.ImmutableRangeSet",
-                  "com.google.common.collect.ImmutableSet",
-                  "com.google.common.collect.ImmutableSetMultimap",
-                  "com.google.common.collect.ImmutableTable")
+                  ImmutableBiMap.class.getCanonicalName(),
+                  ImmutableList.class.getCanonicalName(),
+                  ImmutableListMultimap.class.getCanonicalName(),
+                  ImmutableMap.class.getCanonicalName(),
+                  ImmutableMultimap.class.getCanonicalName(),
+                  ImmutableMultiset.class.getCanonicalName(),
+                  ImmutableRangeMap.class.getCanonicalName(),
+                  ImmutableRangeSet.class.getCanonicalName(),
+                  ImmutableSet.class.getCanonicalName(),
+                  ImmutableSetMultimap.class.getCanonicalName(),
+                  ImmutableTable.class.getCanonicalName())
               .named("copyOf"),
-          staticMethod()
-              .onClass("com.google.errorprone.matchers.Matchers")
-              .namedAnyOf("allOf", "anyOf"),
+          staticMethod().onClass(Instant.class.getCanonicalName()).namedAnyOf("from"),
+          staticMethod().onClass(Matchers.class.getCanonicalName()).namedAnyOf("allOf", "anyOf"),
           staticMethod().onClass("reactor.adapter.rxjava.RxJava2Adapter"),
           staticMethod()
               .onClass("reactor.core.publisher.Flux")
@@ -114,8 +127,9 @@ public final class IdentityConversion extends BugChecker implements MethodInvoca
 
     return buildDescription(tree)
         .setMessage(
-            "This method invocation appears redundant; remove it or suppress this warning and "
-                + "add a comment explaining its purpose")
+            """
+            This method invocation appears redundant; remove it or suppress this warning and add a \
+            comment explaining its purpose""")
         .addFix(SuggestedFix.replace(tree, SourceCode.treeToString(sourceTree, state)))
         .addFix(SuggestedFixes.addSuppressWarnings(state, canonicalName()))
         .build();

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

@@ -11,7 +11,7 @@ import static com.google.errorprone.matchers.Matchers.hasModifier;
 import static com.google.errorprone.matchers.Matchers.isSubtypeOf;
 import static com.google.errorprone.matchers.Matchers.methodReturns;
 import static com.google.errorprone.matchers.Matchers.not;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
 import com.google.errorprone.BugPattern;
@@ -43,8 +43,9 @@ import javax.lang.model.element.Modifier;
 @AutoService(BugChecker.class)
 @BugPattern(
     summary =
-        "`SortedSet` properties of a `@Value.Immutable` or `@Value.Modifiable` type must be "
-            + "annotated with `@Value.NaturalOrder` or `@Value.ReverseOrder`",
+        """
+        `SortedSet` properties of a `@Value.Immutable` or `@Value.Modifiable` type must be \
+        annotated with `@Value.NaturalOrder` or `@Value.ReverseOrder`""",
     link = BUG_PATTERNS_BASE_URL + "ImmutablesSortedSetComparator",
     linkType = CUSTOM,
     severity = ERROR,

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

@@ -3,7 +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 tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
 import com.google.common.collect.Iterables;
@@ -16,17 +16,17 @@ import com.google.errorprone.matchers.Description;
 import com.google.errorprone.util.ASTHelpers;
 import com.sun.source.tree.InstanceOfTree;
 import com.sun.source.tree.LambdaExpressionTree;
-import com.sun.source.tree.Tree.Kind;
 import com.sun.source.tree.VariableTree;
-import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+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::isInstance}.
- *
- * @see MethodReferenceUsage
  */
-// XXX: Consider folding this logic into the `MethodReferenceUsage` check.
+// 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",
@@ -42,12 +42,12 @@ public final class IsInstanceLambdaUsage extends BugChecker implements LambdaExp
 
   @Override
   public Description matchLambdaExpression(LambdaExpressionTree tree, VisitorState state) {
-    if (tree.getParameters().size() != 1 || tree.getBody().getKind() != Kind.INSTANCE_OF) {
+    if (tree.getParameters().size() != 1
+        || !(tree.getBody() instanceof InstanceOfTree instanceOf)) {
       return Description.NO_MATCH;
     }
 
     VariableTree param = Iterables.getOnlyElement(tree.getParameters());
-    InstanceOfTree instanceOf = (InstanceOfTree) tree.getBody();
     if (!ASTHelpers.getSymbol(param).equals(ASTHelpers.getSymbol(instanceOf.getExpression()))) {
       return Description.NO_MATCH;
     }

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

@@ -11,12 +11,12 @@ import static com.google.errorprone.matchers.Matchers.hasMethod;
 import static com.google.errorprone.matchers.Matchers.hasModifier;
 import static com.google.errorprone.matchers.Matchers.isType;
 import static com.google.errorprone.matchers.Matchers.not;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
-import static tech.picnic.errorprone.bugpatterns.util.MoreJUnitMatchers.TEST_METHOD;
-import static tech.picnic.errorprone.bugpatterns.util.MoreMatchers.hasMetaAnnotation;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
+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/JUnitMethodDeclaration.java

@@ -8,9 +8,9 @@ import static com.google.errorprone.matchers.Matchers.enclosingClass;
 import static com.google.errorprone.matchers.Matchers.hasModifier;
 import static com.google.errorprone.matchers.Matchers.not;
 import static java.util.function.Predicate.not;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
-import static tech.picnic.errorprone.bugpatterns.util.MoreJUnitMatchers.SETUP_OR_TEARDOWN_METHOD;
-import static tech.picnic.errorprone.bugpatterns.util.MoreJUnitMatchers.TEST_METHOD;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.MoreJUnitMatchers.SETUP_OR_TEARDOWN_METHOD;
+import static tech.picnic.errorprone.utils.MoreJUnitMatchers.TEST_METHOD;
 
 import com.google.auto.service.AutoService;
 import com.google.common.collect.ImmutableSet;
@@ -28,7 +28,7 @@ import com.sun.source.tree.MethodTree;
 import com.sun.tools.javac.code.Symbol.MethodSymbol;
 import java.util.Optional;
 import javax.lang.model.element.Modifier;
-import tech.picnic.errorprone.bugpatterns.util.ConflictDetection;
+import tech.picnic.errorprone.utils.ConflictDetection;
 
 /** A {@link BugChecker} that flags non-canonical JUnit method declarations. */
 // XXX: Consider introducing a class-level check that enforces that test classes:
@@ -101,6 +101,8 @@ public final class JUnitMethodDeclaration extends BugChecker implements MethodTr
             .build());
   }
 
+  // XXX: Consider dropping leading underscores that otherwise result when canonicalizing
+  // `test_some_method_name`.
   private static Optional<String> tryCanonicalizeMethodName(MethodSymbol symbol) {
     return Optional.of(symbol.getQualifiedName().toString())
         .filter(name -> name.startsWith(TEST_PREFIX))

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

@@ -7,8 +7,8 @@ import static com.google.errorprone.matchers.ChildMultiMatcher.MatchType.AT_LEAS
 import static com.google.errorprone.matchers.Matchers.annotations;
 import static com.google.errorprone.matchers.Matchers.anyOf;
 import static com.google.errorprone.matchers.Matchers.isType;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
-import static tech.picnic.errorprone.bugpatterns.util.MoreMatchers.hasMetaAnnotation;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.MoreMatchers.hasMetaAnnotation;
 
 import com.google.auto.service.AutoService;
 import com.google.errorprone.BugPattern;
@@ -23,7 +23,7 @@ import com.google.errorprone.matchers.MultiMatcher;
 import com.google.errorprone.matchers.MultiMatcher.MultiMatchResult;
 import com.sun.source.tree.AnnotationTree;
 import com.sun.source.tree.MethodTree;
-import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+import tech.picnic.errorprone.utils.SourceCode;
 
 /**
  * A {@link BugChecker} that flags nullary {@link

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

@@ -19,17 +19,20 @@ import static com.google.errorprone.matchers.Matchers.staticMethod;
 import static com.google.errorprone.matchers.Matchers.toType;
 import static java.util.function.Predicate.not;
 import static java.util.stream.Collectors.joining;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
-import static tech.picnic.errorprone.bugpatterns.util.MoreJUnitMatchers.HAS_METHOD_SOURCE;
-import static tech.picnic.errorprone.bugpatterns.util.MoreJUnitMatchers.getMethodSourceFactoryNames;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.MoreJUnitMatchers.HAS_METHOD_SOURCE;
+import static tech.picnic.errorprone.utils.MoreJUnitMatchers.getMethodSourceFactoryNames;
 
 import com.google.auto.service.AutoService;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
 import com.google.errorprone.BugPattern;
 import com.google.errorprone.VisitorState;
 import com.google.errorprone.bugpatterns.BugChecker;
 import com.google.errorprone.bugpatterns.BugChecker.MethodTreeMatcher;
 import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.fixes.SuggestedFixes;
 import com.google.errorprone.matchers.Description;
 import com.google.errorprone.matchers.Matcher;
 import com.google.errorprone.util.ASTHelpers;
@@ -55,7 +58,7 @@ import java.util.stream.IntStream;
 import java.util.stream.LongStream;
 import java.util.stream.Stream;
 import org.jspecify.annotations.Nullable;
-import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+import tech.picnic.errorprone.utils.SourceCode;
 
 /**
  * A {@link BugChecker} that flags JUnit tests with a {@link
@@ -99,14 +102,14 @@ public final class JUnitValueSource extends BugChecker implements MethodTreeMatc
           allOf(
               staticMethod()
                   .onClassAny(
-                      Stream.class.getName(),
-                      IntStream.class.getName(),
-                      LongStream.class.getName(),
-                      DoubleStream.class.getName(),
-                      List.class.getName(),
-                      Set.class.getName(),
-                      "com.google.common.collect.ImmutableList",
-                      "com.google.common.collect.ImmutableSet")
+                      Stream.class.getCanonicalName(),
+                      IntStream.class.getCanonicalName(),
+                      LongStream.class.getCanonicalName(),
+                      DoubleStream.class.getCanonicalName(),
+                      List.class.getCanonicalName(),
+                      Set.class.getCanonicalName(),
+                      ImmutableList.class.getCanonicalName(),
+                      ImmutableSet.class.getCanonicalName())
                   .named("of"),
               hasArguments(AT_LEAST_ONE, anything()),
               hasArguments(ALL, SUPPORTED_VALUE_FACTORY_VALUES)));
@@ -199,16 +202,21 @@ public final class JUnitValueSource extends BugChecker implements MethodTreeMatc
     return getSingleReturnExpression(valueFactoryMethod)
         .flatMap(expression -> tryExtractValueSourceAttributeValue(expression, state))
         .map(
-            valueSourceAttributeValue ->
-                SuggestedFix.builder()
-                    .addImport("org.junit.jupiter.params.provider.ValueSource")
-                    .replace(
-                        methodSourceAnnotation,
-                        String.format(
-                            "@ValueSource(%s = %s)",
-                            toValueSourceAttributeName(parameterType), valueSourceAttributeValue))
-                    .delete(valueFactoryMethod)
-                    .build());
+            valueSourceAttributeValue -> {
+              SuggestedFix.Builder fix = SuggestedFix.builder();
+              String valueSource =
+                  SuggestedFixes.qualifyType(
+                      state, fix, "org.junit.jupiter.params.provider.ValueSource");
+              return fix.replace(
+                      methodSourceAnnotation,
+                      String.format(
+                          "@%s(%s = %s)",
+                          valueSource,
+                          toValueSourceAttributeName(parameterType),
+                          valueSourceAttributeValue))
+                  .delete(valueFactoryMethod)
+                  .build();
+            });
   }
 
   // XXX: This pattern also occurs a few times inside Error Prone; contribute upstream.
@@ -224,7 +232,7 @@ public final class JUnitValueSource extends BugChecker implements MethodTreeMatc
       @Override
       public @Nullable Void visitReturn(ReturnTree node, @Nullable Void unused) {
         returnExpressions.add(node.getExpression());
-        return super.visitReturn(node, unused);
+        return super.visitReturn(node, null);
       }
 
       @Override
@@ -257,8 +265,8 @@ public final class JUnitValueSource extends BugChecker implements MethodTreeMatc
             arguments.stream()
                 .map(
                     arg ->
-                        arg instanceof MethodInvocationTree
-                            ? Iterables.getOnlyElement(((MethodInvocationTree) arg).getArguments())
+                        arg instanceof MethodInvocationTree methodInvocation
+                            ? Iterables.getOnlyElement(methodInvocation.getArguments())
                             : arg)
                 .map(argument -> SourceCode.treeToString(argument, state))
                 .collect(joining(", ")))
@@ -268,16 +276,12 @@ public final class JUnitValueSource extends BugChecker implements MethodTreeMatc
   private static String toValueSourceAttributeName(Type type) {
     String typeString = type.tsym.name.toString();
 
-    switch (typeString) {
-      case "Class":
-        return "classes";
-      case "Character":
-        return "chars";
-      case "Integer":
-        return "ints";
-      default:
-        return typeString.toLowerCase(Locale.ROOT) + 's';
-    }
+    return switch (typeString) {
+      case "Class" -> "classes";
+      case "Character" -> "chars";
+      case "Integer" -> "ints";
+      default -> typeString.toLowerCase(Locale.ROOT) + 's';
+    };
   }
 
   private static <T> Optional<T> getElementIfSingleton(Collection<T> collection) {
@@ -289,11 +293,10 @@ public final class JUnitValueSource extends BugChecker implements MethodTreeMatc
   private static Matcher<ExpressionTree> isSingleDimensionArrayCreationWithAllElementsMatching(
       Matcher<? super ExpressionTree> elementMatcher) {
     return (tree, state) -> {
-      if (!(tree instanceof NewArrayTree)) {
+      if (!(tree instanceof NewArrayTree newArray)) {
         return false;
       }
 
-      NewArrayTree newArray = (NewArrayTree) tree;
       return newArray.getDimensions().isEmpty()
           && !newArray.getInitializers().isEmpty()
           && newArray.getInitializers().stream()

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

@@ -7,13 +7,14 @@ import static com.google.errorprone.BugPattern.StandardTags.STYLE;
 import static java.util.Comparator.comparing;
 import static java.util.Comparator.naturalOrder;
 import static java.util.stream.Collectors.joining;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
 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;
@@ -31,20 +32,17 @@ import com.sun.source.tree.LiteralTree;
 import com.sun.source.tree.NewArrayTree;
 import com.sun.source.tree.PrimitiveTypeTree;
 import com.sun.source.tree.Tree;
-import com.sun.source.tree.Tree.Kind;
 import com.sun.source.util.TreeScanner;
 import com.sun.tools.javac.code.Symtab;
 import com.sun.tools.javac.code.Type;
-import java.util.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;
-import tech.picnic.errorprone.bugpatterns.util.AnnotationAttributeMatcher;
-import tech.picnic.errorprone.bugpatterns.util.Flags;
-import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+import tech.picnic.errorprone.utils.AnnotationAttributeMatcher;
+import tech.picnic.errorprone.utils.Flags;
+import tech.picnic.errorprone.utils.SourceCode;
 
 /**
  * A {@link BugChecker} that flags annotation array listings which aren't sorted lexicographically.
@@ -52,6 +50,9 @@ import tech.picnic.errorprone.bugpatterns.util.SourceCode;
  * <p>The idea behind this checker is that maintaining a sorted sequence simplifies conflict
  * resolution, and can even avoid it if two branches add the same entry.
  */
+// XXX: In some places we declare a `@SuppressWarnings` annotation with a final value of
+// `key-to-resolve-AnnotationUseStyle-and-TrailingComment-check-conflict`. That entry must stay
+// last. Consider adding (generic?) support for such cases.
 @AutoService(BugChecker.class)
 @BugPattern(
     summary = "Where possible, sort annotation array attributes lexicographically",
@@ -65,14 +66,15 @@ public final class LexicographicalAnnotationAttributeListing extends BugChecker
   private static final long serialVersionUID = 1L;
   private static final ImmutableSet<String> BLACKLISTED_ANNOTATIONS =
       ImmutableSet.of(
-          // XXX: unless JsonPropertyOrder#alphabetic is true...
+          // XXX: Unless `JsonPropertyOrder#alphabetic` is true...
           "com.fasterxml.jackson.annotation.JsonPropertyOrder#value",
           "io.swagger.annotations.ApiImplicitParams#value",
           "io.swagger.v3.oas.annotations.Parameters#value",
           "javax.xml.bind.annotation.XmlType#propOrder",
           "org.springframework.context.annotation.PropertySource#value",
           "org.springframework.test.context.TestPropertySource#locations",
-          "org.springframework.test.context.TestPropertySource#value");
+          "org.springframework.test.context.TestPropertySource#value",
+          "picocli.CommandLine.Option#names");
   private static final String FLAG_PREFIX = "LexicographicalAnnotationAttributeListing:";
   private static final String INCLUDED_ANNOTATIONS_FLAG = FLAG_PREFIX + "Includes";
   private static final String EXCLUDED_ANNOTATIONS_FLAG = FLAG_PREFIX + "Excludes";
@@ -122,13 +124,9 @@ public final class LexicographicalAnnotationAttributeListing extends BugChecker
   }
 
   private static Optional<NewArrayTree> extractArray(ExpressionTree expr) {
-    if (expr.getKind() == Kind.ASSIGNMENT) {
-      return extractArray(((AssignmentTree) expr).getExpression());
-    }
-
-    return Optional.of(expr)
-        .filter(e -> e.getKind() == Kind.NEW_ARRAY)
-        .map(NewArrayTree.class::cast);
+    return expr instanceof AssignmentTree assignment
+        ? extractArray(assignment.getExpression())
+        : Optional.of(expr).filter(NewArrayTree.class::isInstance).map(NewArrayTree.class::cast);
   }
 
   private static Optional<SuggestedFix.Builder> suggestSorting(
@@ -164,7 +162,12 @@ 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));
   }
 
@@ -193,24 +196,24 @@ public final class LexicographicalAnnotationAttributeListing extends BugChecker
       @Override
       public @Nullable Void visitIdentifier(IdentifierTree node, @Nullable Void unused) {
         nodes.add(ImmutableList.of(node.getName().toString()));
-        return super.visitIdentifier(node, unused);
+        return super.visitIdentifier(node, null);
       }
 
       @Override
       public @Nullable Void visitLiteral(LiteralTree node, @Nullable Void unused) {
         Object value = ASTHelpers.constValue(node);
         nodes.add(
-            value instanceof String
-                ? STRING_ARGUMENT_SPLITTER.splitToStream((String) value).collect(toImmutableList())
+            value instanceof String str
+                ? STRING_ARGUMENT_SPLITTER.splitToStream(str).collect(toImmutableList())
                 : ImmutableList.of(String.valueOf(value)));
 
-        return super.visitLiteral(node, unused);
+        return super.visitLiteral(node, null);
       }
 
       @Override
       public @Nullable Void visitPrimitiveType(PrimitiveTypeTree node, @Nullable Void unused) {
         nodes.add(ImmutableList.of(node.getPrimitiveTypeKind().toString()));
-        return super.visitPrimitiveType(node, unused);
+        return super.visitPrimitiveType(node, null);
       }
     }.scan(array, null);
 
@@ -226,10 +229,8 @@ 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

@@ -7,7 +7,7 @@ import static com.google.errorprone.BugPattern.StandardTags.STYLE;
 import static com.sun.tools.javac.code.TypeAnnotations.AnnotationType.DECLARATION;
 import static com.sun.tools.javac.code.TypeAnnotations.AnnotationType.TYPE;
 import static java.util.Comparator.comparing;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
 import com.google.common.base.VerifyException;
@@ -28,7 +28,7 @@ import com.sun.tools.javac.code.TypeAnnotations.AnnotationType;
 import java.util.Comparator;
 import java.util.List;
 import org.jspecify.annotations.Nullable;
-import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+import tech.picnic.errorprone.utils.SourceCode;
 
 /**
  * A {@link BugChecker} that flags annotations that are not lexicographically sorted.
@@ -36,6 +36,10 @@ import tech.picnic.errorprone.bugpatterns.util.SourceCode;
  * <p>The idea behind this checker is that maintaining a sorted sequence simplifies conflict
  * resolution, and can even avoid it if two branches add the same annotation.
  */
+// XXX: Currently this checker only flags method-level annotations. It should likely also flag
+// type-, field- and parameter-level annotations.
+// XXX: Duplicate entries are often a mistake. Consider introducing a similar `BugChecker` that
+// flags duplicates.
 @AutoService(BugChecker.class)
 @BugPattern(
     summary = "Sort annotations lexicographically where possible",

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

@@ -9,7 +9,7 @@ import static com.google.errorprone.matchers.Matchers.isSameType;
 import static com.google.errorprone.matchers.Matchers.isVariable;
 import static com.google.errorprone.matchers.Matchers.not;
 import static com.google.errorprone.matchers.Matchers.staticMethod;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
 import com.google.errorprone.BugPattern;
@@ -25,7 +25,7 @@ import com.sun.source.tree.MethodInvocationTree;
 import com.sun.source.tree.Tree;
 import com.sun.source.tree.VariableTree;
 import java.util.List;
-import tech.picnic.errorprone.bugpatterns.util.MoreASTHelpers;
+import tech.picnic.errorprone.utils.MoreASTHelpers;
 
 /**
  * A {@link BugChecker} that flags the use of {@link org.mockito.Mockito#mock(Class)} and {@link
@@ -50,7 +50,7 @@ public final class MockitoMockClassReference extends BugChecker
   private static final long serialVersionUID = 1L;
   private static final Matcher<MethodInvocationTree> MOCKITO_MOCK_OR_SPY_WITH_HARDCODED_TYPE =
       allOf(
-          argument(0, allOf(isSameType(Class.class.getName()), not(isVariable()))),
+          argument(0, allOf(isSameType(Class.class.getCanonicalName()), not(isVariable()))),
           staticMethod().onClass("org.mockito.Mockito").namedAnyOf("mock", "spy"));
 
   /** Instantiates a new {@link MockitoMockClassReference} instance. */
@@ -67,20 +67,19 @@ public final class MockitoMockClassReference extends BugChecker
     return describeMatch(tree, SuggestedFixes.removeElement(arguments.get(0), arguments, state));
   }
 
+  // XXX: Use switch pattern matching once the targeted JDK supports this.
   private static boolean isTypeDerivableFromContext(MethodInvocationTree tree, VisitorState state) {
     Tree parent = state.getPath().getParentPath().getLeaf();
-    switch (parent.getKind()) {
-      case VARIABLE:
-        return !ASTHelpers.hasImplicitType((VariableTree) parent, state)
-            && MoreASTHelpers.areSameType(tree, parent, state);
-      case ASSIGNMENT:
-        return MoreASTHelpers.areSameType(tree, parent, state);
-      case RETURN:
-        return MoreASTHelpers.findMethodExitedOnReturn(state)
-            .filter(m -> MoreASTHelpers.areSameType(tree, m.getReturnType(), state))
-            .isPresent();
-      default:
-        return false;
-    }
+    return switch (parent.getKind()) {
+      case VARIABLE ->
+          !ASTHelpers.hasImplicitType((VariableTree) parent, state)
+              && MoreASTHelpers.areSameType(tree, parent, state);
+      case ASSIGNMENT -> MoreASTHelpers.areSameType(tree, parent, state);
+      case RETURN ->
+          MoreASTHelpers.findMethodExitedOnReturn(state)
+              .filter(m -> MoreASTHelpers.areSameType(tree, m.getReturnType(), state))
+              .isPresent();
+      default -> false;
+    };
   }
 }

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

@@ -4,7 +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.SIMPLIFICATION;
 import static com.google.errorprone.matchers.Matchers.staticMethod;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
 import com.google.common.collect.Iterables;
@@ -18,7 +18,7 @@ import com.google.errorprone.matchers.Matcher;
 import com.sun.source.tree.ExpressionTree;
 import com.sun.source.tree.MethodInvocationTree;
 import java.util.List;
-import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+import tech.picnic.errorprone.utils.SourceCode;
 
 /**
  * A {@link BugChecker} that flags method invocations for which all arguments are wrapped using

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

@@ -4,7 +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.PERFORMANCE;
 import static com.google.errorprone.matchers.method.MethodMatchers.staticMethod;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
 import com.google.errorprone.BugPattern;
@@ -24,7 +24,9 @@ import com.sun.source.tree.MethodInvocationTree;
 @AutoService(BugChecker.class)
 @BugPattern(
     summary =
-        "Avoid MongoDB's `$text` filter operator, as it can trigger heavy queries and even cause the server to run out of memory",
+        """
+        Avoid MongoDB's `$text` filter operator, as it can trigger heavy queries and even cause \
+        the server to run out of memory""",
     link = BUG_PATTERNS_BASE_URL + "MongoDBTextFilterUsage",
     linkType = CUSTOM,
     severity = SUGGESTION,

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

@@ -3,11 +3,11 @@ 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.FRAGILE_CODE;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
-import static tech.picnic.errorprone.bugpatterns.util.MoreMatchers.isSubTypeOf;
-import static tech.picnic.errorprone.bugpatterns.util.MoreTypes.generic;
-import static tech.picnic.errorprone.bugpatterns.util.MoreTypes.raw;
-import static tech.picnic.errorprone.bugpatterns.util.MoreTypes.subOf;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.MoreMatchers.isSubTypeOf;
+import static tech.picnic.errorprone.utils.MoreTypes.generic;
+import static tech.picnic.errorprone.utils.MoreTypes.raw;
+import static tech.picnic.errorprone.utils.MoreTypes.subOf;
 
 import com.google.auto.service.AutoService;
 import com.google.errorprone.BugPattern;

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

@@ -6,13 +6,13 @@ import static com.google.errorprone.BugPattern.StandardTags.FRAGILE_CODE;
 import static com.google.errorprone.matchers.Matchers.typePredicateMatcher;
 import static com.google.errorprone.predicates.TypePredicates.allOf;
 import static com.google.errorprone.predicates.TypePredicates.not;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
-import static tech.picnic.errorprone.bugpatterns.util.MoreTypePredicates.hasTypeParameter;
-import static tech.picnic.errorprone.bugpatterns.util.MoreTypePredicates.isSubTypeOf;
-import static tech.picnic.errorprone.bugpatterns.util.MoreTypes.generic;
-import static tech.picnic.errorprone.bugpatterns.util.MoreTypes.raw;
-import static tech.picnic.errorprone.bugpatterns.util.MoreTypes.subOf;
-import static tech.picnic.errorprone.bugpatterns.util.MoreTypes.type;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.MoreTypePredicates.hasTypeParameter;
+import static tech.picnic.errorprone.utils.MoreTypePredicates.isSubTypeOf;
+import static tech.picnic.errorprone.utils.MoreTypes.generic;
+import static tech.picnic.errorprone.utils.MoreTypes.raw;
+import static tech.picnic.errorprone.utils.MoreTypes.subOf;
+import static tech.picnic.errorprone.utils.MoreTypes.type;
 
 import com.google.auto.service.AutoService;
 import com.google.errorprone.BugPattern;
@@ -34,8 +34,9 @@ import com.sun.tools.javac.code.Type;
 @AutoService(BugChecker.class)
 @BugPattern(
     summary =
-        "Avoid `Publisher`s that emit other `Publishers`s; "
-            + "the resultant code is hard to reason about",
+        """
+        Avoid `Publisher`s that emit other `Publishers`s; the resultant code is hard to reason \
+        about""",
     link = BUG_PATTERNS_BASE_URL + "NestedPublishers",
     linkType = CUSTOM,
     severity = WARNING,

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

@@ -5,7 +5,7 @@ import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
 import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
 import static com.google.errorprone.matchers.Matchers.anyOf;
 import static com.google.errorprone.matchers.Matchers.instanceMethod;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
 import com.google.errorprone.BugPattern;
@@ -20,7 +20,7 @@ import com.sun.source.tree.ExpressionTree;
 import com.sun.source.tree.MethodInvocationTree;
 import java.util.function.BiFunction;
 import reactor.core.publisher.Mono;
-import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+import tech.picnic.errorprone.utils.SourceCode;
 
 /**
  * A {@link BugChecker} that flags {@link Mono} operations that are known to be vacuous, given that
@@ -72,7 +72,7 @@ public final class NonEmptyMono extends BugChecker implements MethodInvocationTr
           instanceMethod()
               .onDescendantOf("reactor.core.publisher.Flux")
               .named("reduce")
-              .withParameters(Object.class.getName(), BiFunction.class.getName()),
+              .withParameters(Object.class.getCanonicalName(), BiFunction.class.getCanonicalName()),
           instanceMethod()
               .onDescendantOf("reactor.core.publisher.Mono")
               .namedAnyOf("defaultIfEmpty", "hasElement", "single"));

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

@@ -4,11 +4,13 @@ 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 tech.picnic.errorprone.bugpatterns.StaticImport.STATIC_IMPORT_CANDIDATE_MEMBERS;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
 import com.google.auto.value.AutoValue;
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Predicates;
+import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.ImmutableSetMultimap;
 import com.google.common.collect.ImmutableTable;
@@ -27,8 +29,15 @@ import com.sun.source.tree.MemberSelectTree;
 import com.sun.source.tree.Tree;
 import com.sun.source.util.TreeScanner;
 import com.sun.tools.javac.code.Symbol;
+import java.time.Clock;
+import java.time.InstantSource;
+import java.time.ZoneOffset;
+import java.util.Collections;
+import java.util.Locale;
+import java.util.Optional;
+import java.util.regex.Pattern;
 import org.jspecify.annotations.Nullable;
-import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+import tech.picnic.errorprone.utils.SourceCode;
 
 /**
  * A {@link BugChecker} that flags static imports of type members that should *not* be statically
@@ -59,10 +68,15 @@ public final class NonStaticImport extends BugChecker implements CompilationUnit
   @VisibleForTesting
   static final ImmutableSet<String> NON_STATIC_IMPORT_CANDIDATE_TYPES =
       ImmutableSet.of(
-          "com.google.common.base.Strings",
+          ASTHelpers.class.getCanonicalName(),
+          Clock.class.getCanonicalName(),
+          InstantSource.class.getCanonicalName(),
+          Strings.class.getCanonicalName(),
+          VisitorState.class.getCanonicalName(),
+          ZoneOffset.class.getCanonicalName(),
           "com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode",
-          "java.time.Clock",
-          "java.time.ZoneOffset");
+          "reactor.core.publisher.Flux",
+          "reactor.core.publisher.Mono");
 
   /**
    * Type members that should never be statically imported.
@@ -81,9 +95,8 @@ public final class NonStaticImport extends BugChecker implements CompilationUnit
   // specific context is left out.
   static final ImmutableSetMultimap<String, String> NON_STATIC_IMPORT_CANDIDATE_MEMBERS =
       ImmutableSetMultimap.<String, String>builder()
-          .put("com.google.common.base.Predicates", "contains")
           .putAll(
-              "java.util.Collections",
+              Collections.class.getCanonicalName(),
               "addAll",
               "copy",
               "fill",
@@ -94,8 +107,10 @@ public final class NonStaticImport extends BugChecker implements CompilationUnit
               "rotate",
               "sort",
               "swap")
-          .put("java.util.Locale", "ROOT")
-          .putAll("java.util.regex.Pattern", "compile", "matches", "quote")
+          .put(Locale.class.getCanonicalName(), "ROOT")
+          .put(Optional.class.getCanonicalName(), "empty")
+          .putAll(Pattern.class.getCanonicalName(), "compile", "matches", "quote")
+          .put(Predicates.class.getCanonicalName(), "contains")
           .put("org.springframework.http.MediaType", "ALL")
           .build();
 
@@ -116,7 +131,7 @@ public final class NonStaticImport extends BugChecker implements CompilationUnit
           "builder",
           "copyOf",
           "create",
-          "empty",
+          "EPOCH",
           "from",
           "getDefaultInstance",
           "INSTANCE",
@@ -127,10 +142,8 @@ public final class NonStaticImport extends BugChecker implements CompilationUnit
           "newBuilder",
           "newInstance",
           "of",
-          "ONE",
           "parse",
-          "valueOf",
-          "ZERO");
+          "valueOf");
 
   /** Instantiates a new {@link NonStaticImport} instance. */
   public NonStaticImport() {}
@@ -159,10 +172,9 @@ public final class NonStaticImport extends BugChecker implements CompilationUnit
         ImmutableTable.builder();
     for (ImportTree importTree : tree.getImports()) {
       Tree qualifiedIdentifier = importTree.getQualifiedIdentifier();
-      if (importTree.isStatic() && qualifiedIdentifier instanceof MemberSelectTree) {
-        MemberSelectTree memberSelectTree = (MemberSelectTree) qualifiedIdentifier;
-        String type = SourceCode.treeToString(memberSelectTree.getExpression(), state);
-        String member = memberSelectTree.getIdentifier().toString();
+      if (importTree.isStatic() && qualifiedIdentifier instanceof MemberSelectTree memberSelect) {
+        String type = SourceCode.treeToString(memberSelect.getExpression(), state);
+        String member = memberSelect.getIdentifier().toString();
         if (shouldNotBeStaticallyImported(type, member)) {
           imports.put(
               type,
@@ -173,7 +185,7 @@ public final class NonStaticImport extends BugChecker implements CompilationUnit
       }
     }
 
-    return imports.build();
+    return imports.buildOrThrow();
   }
 
   private static boolean shouldNotBeStaticallyImported(String type, String member) {
@@ -201,7 +213,7 @@ public final class NonStaticImport extends BugChecker implements CompilationUnit
           }
         }
 
-        return super.visitIdentifier(node, unused);
+        return super.visitIdentifier(node, null);
       }
     }.scan(tree, null);
   }

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

@@ -0,0 +1,123 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.NONE;
+import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
+import static com.google.errorprone.BugPattern.StandardTags.PERFORMANCE;
+import static com.google.errorprone.matchers.Matchers.instanceMethod;
+import static com.google.errorprone.matchers.Matchers.staticMethod;
+import static java.util.stream.Collectors.joining;
+
+import com.google.auto.service.AutoService;
+import com.google.common.collect.Iterables;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.fixes.SuggestedFixes;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.google.errorprone.refaster.Refaster;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.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;
+
+/**
+ * A {@link BugChecker} that flags arguments to {@link Optional#orElse(Object)} that should be
+ * deferred using {@link Optional#orElseGet(Supplier)}.
+ *
+ * <p>The suggested fix assumes that the argument to {@code orElse} does not have side effects. If
+ * 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: 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 =
+        """
+        Prefer `Optional#orElseGet` over `Optional#orElse` if the fallback requires additional \
+        computation""",
+    linkType = NONE,
+    severity = WARNING,
+    tags = PERFORMANCE)
+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 OptionalOrElseGet} instance. */
+  public OptionalOrElseGet() {}
+
+  @Override
+  public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    if (!OPTIONAL_OR_ELSE_METHOD.matches(tree, state)) {
+      return Description.NO_MATCH;
+    }
+
+    ExpressionTree argument = Iterables.getOnlyElement(tree.getArguments());
+    if (!REQUIRES_COMPUTATION.matches(argument, state)
+        || REFASTER_METHOD.matches(argument, state)) {
+      return Description.NO_MATCH;
+    }
+
+    /*
+     * We have a match. Construct the method reference or lambda expression to be passed to the
+     * replacement `#orElseGet` invocation.
+     */
+    String newArgument =
+        tryMethodReferenceConversion(argument, state)
+            .orElseGet(() -> "() -> " + SourceCode.treeToString(argument, state));
+
+    /* Construct the suggested fix, replacing the method invocation and its argument. */
+    SuggestedFix fix =
+        SuggestedFix.builder()
+            .merge(SuggestedFixes.renameMethodInvocation(tree, "orElseGet", state))
+            .replace(argument, newArgument)
+            .build();
+
+    return describeMatch(tree, fix);
+  }
+
+  /** Returns the nullary method reference matching the given expression, if any. */
+  private static Optional<String> tryMethodReferenceConversion(
+      ExpressionTree tree, VisitorState state) {
+    if (!(tree instanceof MethodInvocationTree methodInvocation)) {
+      return Optional.empty();
+    }
+
+    if (!methodInvocation.getArguments().isEmpty()) {
+      return Optional.empty();
+    }
+
+    if (!(methodInvocation.getMethodSelect() instanceof MemberSelectTree memberSelect)) {
+      return Optional.empty();
+    }
+
+    if (REQUIRES_COMPUTATION.matches(memberSelect.getExpression(), state)) {
+      return Optional.empty();
+    }
+
+    return Optional.of(
+        SourceCode.treeToString(memberSelect.getExpression(), state)
+            + "::"
+            + (methodInvocation.getTypeArguments().isEmpty()
+                ? ""
+                : methodInvocation.getTypeArguments().stream()
+                    .map(arg -> SourceCode.treeToString(arg, state))
+                    .collect(joining(",", "<", ">")))
+            + memberSelect.getIdentifier());
+  }
+}

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

@@ -7,7 +7,7 @@ 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.stream.Collectors.joining;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
 import com.google.common.base.VerifyException;
@@ -17,10 +17,12 @@ import com.google.errorprone.bugpatterns.BugChecker;
 import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
 import com.google.errorprone.fixes.Fix;
 import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.fixes.SuggestedFixes;
 import com.google.errorprone.matchers.Description;
 import com.google.errorprone.matchers.Matcher;
 import com.google.errorprone.util.ASTHelpers;
 import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.IdentifierTree;
 import com.sun.source.tree.LambdaExpressionTree;
 import com.sun.source.tree.MemberSelectTree;
 import com.sun.source.tree.MethodInvocationTree;
@@ -32,7 +34,7 @@ import java.util.Comparator;
 import java.util.Optional;
 import java.util.function.Function;
 import java.util.stream.Stream;
-import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+import tech.picnic.errorprone.utils.SourceCode;
 
 /**
  * A {@link BugChecker} that flags {@code Comparator#comparing*} invocations that can be replaced
@@ -43,8 +45,9 @@ import tech.picnic.errorprone.bugpatterns.util.SourceCode;
 @AutoService(BugChecker.class)
 @BugPattern(
     summary =
-        "Ensure invocations of `Comparator#comparing{,Double,Int,Long}` match the return type"
-            + " of the provided function",
+        """
+        Ensure invocations of `Comparator#comparing{,Double,Int,Long}` match the return type of \
+        the provided function""",
     link = BUG_PATTERNS_BASE_URL + "PrimitiveComparison",
     linkType = CUSTOM,
     severity = WARNING,
@@ -55,21 +58,21 @@ public final class PrimitiveComparison extends BugChecker implements MethodInvoc
   private static final Matcher<ExpressionTree> STATIC_COMPARISON_METHOD =
       anyOf(
           staticMethod()
-              .onClass(Comparator.class.getName())
+              .onClass(Comparator.class.getCanonicalName())
               .namedAnyOf("comparingInt", "comparingLong", "comparingDouble"),
           staticMethod()
-              .onClass(Comparator.class.getName())
+              .onClass(Comparator.class.getCanonicalName())
               .named("comparing")
-              .withParameters(Function.class.getName()));
+              .withParameters(Function.class.getCanonicalName()));
   private static final Matcher<ExpressionTree> INSTANCE_COMPARISON_METHOD =
       anyOf(
           instanceMethod()
-              .onDescendantOf(Comparator.class.getName())
+              .onDescendantOf(Comparator.class.getCanonicalName())
               .namedAnyOf("thenComparingInt", "thenComparingLong", "thenComparingDouble"),
           instanceMethod()
-              .onDescendantOf(Comparator.class.getName())
+              .onDescendantOf(Comparator.class.getCanonicalName())
               .named("thenComparing")
-              .withParameters(Function.class.getName()));
+              .withParameters(Function.class.getCanonicalName()));
 
   /** Instantiates a new {@link PrimitiveComparison} instance. */
   public PrimitiveComparison() {}
@@ -146,37 +149,44 @@ public final class PrimitiveComparison extends BugChecker implements MethodInvoc
     return isStatic ? "comparing" : "thenComparing";
   }
 
+  // XXX: Use switch pattern matching once the targeted JDK supports this.
   private static Optional<Type> getPotentiallyBoxedReturnType(ExpressionTree tree) {
-    switch (tree.getKind()) {
-      case LAMBDA_EXPRESSION:
-        /* Return the lambda expression's actual return type. */
-        return Optional.ofNullable(ASTHelpers.getType(((LambdaExpressionTree) tree).getBody()));
-      case MEMBER_REFERENCE:
-        /* Return the method's declared return type. */
-        // XXX: Very fragile. Do better.
-        Type subType2 = ((JCMemberReference) tree).referentType;
-        return Optional.of(subType2.getReturnType());
-      default:
-        /* This appears to be a genuine `{,ToInt,ToLong,ToDouble}Function`. */
-        return Optional.empty();
+    if (tree instanceof LambdaExpressionTree lambdaExpression) {
+      /* Return the lambda expression's actual return type. */
+      return Optional.ofNullable(ASTHelpers.getType(lambdaExpression.getBody()));
     }
+
+    // XXX: The match against a concrete type and reference to one of its fields is fragile. Do
+    // better.
+    if (tree instanceof JCMemberReference memberReference) {
+      /* Return the method's declared return type. */
+      Type subType = memberReference.referentType;
+      return Optional.of(subType.getReturnType());
+    }
+
+    /* This appears to be a genuine `{,ToInt,ToLong,ToDouble}Function`. */
+    return Optional.empty();
   }
 
+  // XXX: Use switch pattern matching once the targeted JDK supports this.
   private static Fix suggestFix(
       MethodInvocationTree tree, String preferredMethodName, VisitorState state) {
     ExpressionTree expr = tree.getMethodSelect();
-    switch (expr.getKind()) {
-      case IDENTIFIER:
-        return SuggestedFix.builder()
-            .addStaticImport(Comparator.class.getName() + '.' + preferredMethodName)
-            .replace(expr, preferredMethodName)
-            .build();
-      case MEMBER_SELECT:
-        MemberSelectTree ms = (MemberSelectTree) tree.getMethodSelect();
-        return SuggestedFix.replace(
-            ms, SourceCode.treeToString(ms.getExpression(), state) + '.' + preferredMethodName);
-      default:
-        throw new VerifyException("Unexpected type of expression: " + expr.getKind());
+
+    if (expr instanceof IdentifierTree) {
+      SuggestedFix.Builder fix = SuggestedFix.builder();
+      String replacement =
+          SuggestedFixes.qualifyStaticImport(
+              Comparator.class.getCanonicalName() + '.' + preferredMethodName, fix, state);
+      return fix.replace(expr, replacement).build();
     }
+
+    if (expr instanceof MemberSelectTree memberSelect) {
+      return SuggestedFix.replace(
+          memberSelect,
+          SourceCode.treeToString(memberSelect.getExpression(), state) + '.' + preferredMethodName);
+    }
+
+    throw new VerifyException("Unexpected type of expression: " + expr.getKind());
   }
 }

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

@@ -15,9 +15,11 @@ import static com.google.errorprone.matchers.Matchers.isSubtypeOf;
 import static com.google.errorprone.matchers.Matchers.not;
 import static com.google.errorprone.matchers.method.MethodMatchers.instanceMethod;
 import static com.google.errorprone.matchers.method.MethodMatchers.staticMethod;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
+import com.google.common.base.Preconditions;
+import com.google.common.base.Verify;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
 import com.google.common.primitives.Primitives;
@@ -51,9 +53,9 @@ import java.util.Objects;
 import java.util.Optional;
 import java.util.stream.Stream;
 import javax.inject.Inject;
-import tech.picnic.errorprone.bugpatterns.util.Flags;
-import tech.picnic.errorprone.bugpatterns.util.MethodMatcherFactory;
-import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+import tech.picnic.errorprone.utils.Flags;
+import tech.picnic.errorprone.utils.MethodMatcherFactory;
+import tech.picnic.errorprone.utils.SourceCode;
 
 /** A {@link BugChecker} that flags redundant explicit string conversions. */
 @AutoService(BugChecker.class)
@@ -86,7 +88,7 @@ public final class RedundantStringConversion extends BugChecker
   private static final Matcher<MethodInvocationTree> WELL_KNOWN_STRING_CONVERSION_METHODS =
       anyOf(
           instanceMethod()
-              .onDescendantOfAny(Object.class.getName())
+              .onDescendantOfAny(Object.class.getCanonicalName())
               .named("toString")
               .withNoParameters(),
           allOf(
@@ -100,7 +102,7 @@ public final class RedundantStringConversion extends BugChecker
                               .collect(toImmutableSet()))
                       .named("toString"),
                   allOf(
-                      staticMethod().onClass(String.class.getName()).named("valueOf"),
+                      staticMethod().onClass(String.class.getCanonicalName()).named("valueOf"),
                       not(
                           anyMethod()
                               .anyClass()
@@ -109,35 +111,37 @@ public final class RedundantStringConversion extends BugChecker
                                   ImmutableList.of(Suppliers.arrayOf(Suppliers.CHAR_TYPE))))))));
   private static final Matcher<ExpressionTree> STRINGBUILDER_APPEND_INVOCATION =
       instanceMethod()
-          .onDescendantOf(StringBuilder.class.getName())
+          .onDescendantOf(StringBuilder.class.getCanonicalName())
           .named("append")
-          .withParameters(String.class.getName());
+          .withParameters(String.class.getCanonicalName());
   private static final Matcher<ExpressionTree> STRINGBUILDER_INSERT_INVOCATION =
       instanceMethod()
-          .onDescendantOf(StringBuilder.class.getName())
+          .onDescendantOf(StringBuilder.class.getCanonicalName())
           .named("insert")
-          .withParameters(int.class.getName(), String.class.getName());
+          .withParameters(int.class.getCanonicalName(), String.class.getCanonicalName());
   private static final Matcher<ExpressionTree> FORMATTER_INVOCATION =
       anyOf(
-          staticMethod().onClass(String.class.getName()).named("format"),
-          instanceMethod().onDescendantOf(Formatter.class.getName()).named("format"),
+          staticMethod().onClass(String.class.getCanonicalName()).named("format"),
+          instanceMethod().onDescendantOf(Formatter.class.getCanonicalName()).named("format"),
           instanceMethod()
-              .onDescendantOfAny(PrintStream.class.getName(), PrintWriter.class.getName())
+              .onDescendantOfAny(
+                  PrintStream.class.getCanonicalName(), PrintWriter.class.getCanonicalName())
               .namedAnyOf("format", "printf"),
           instanceMethod()
-              .onDescendantOfAny(PrintStream.class.getName(), PrintWriter.class.getName())
+              .onDescendantOfAny(
+                  PrintStream.class.getCanonicalName(), PrintWriter.class.getCanonicalName())
               .namedAnyOf("print", "println")
-              .withParameters(Object.class.getName()),
+              .withParameters(Object.class.getCanonicalName()),
           staticMethod()
-              .onClass(Console.class.getName())
+              .onClass(Console.class.getCanonicalName())
               .namedAnyOf("format", "printf", "readline", "readPassword"));
   private static final Matcher<ExpressionTree> GUAVA_GUARD_INVOCATION =
       anyOf(
           staticMethod()
-              .onClass("com.google.common.base.Preconditions")
+              .onClass(Preconditions.class.getCanonicalName())
               .namedAnyOf("checkArgument", "checkState", "checkNotNull"),
           staticMethod()
-              .onClass("com.google.common.base.Verify")
+              .onClass(Verify.class.getCanonicalName())
               .namedAnyOf("verify", "verifyNotNull"));
   private static final Matcher<ExpressionTree> SLF4J_LOGGER_INVOCATION =
       instanceMethod()
@@ -327,36 +331,32 @@ public final class RedundantStringConversion extends BugChecker
   }
 
   private Optional<ExpressionTree> trySimplify(ExpressionTree tree, VisitorState state) {
-    if (tree.getKind() != Kind.METHOD_INVOCATION) {
+    if (!(tree instanceof MethodInvocationTree methodInvocation)) {
       return Optional.empty();
     }
 
-    MethodInvocationTree methodInvocation = (MethodInvocationTree) tree;
     if (!conversionMethodMatcher.matches(methodInvocation, state)) {
       return Optional.empty();
     }
 
-    switch (methodInvocation.getArguments().size()) {
-      case 0:
-        return trySimplifyNullaryMethod(methodInvocation, state);
-      case 1:
-        return trySimplifyUnaryMethod(methodInvocation, state);
-      default:
-        throw new IllegalStateException(
-            "Cannot simplify method call with two or more arguments: "
-                + SourceCode.treeToString(tree, state));
-    }
+    return switch (methodInvocation.getArguments().size()) {
+      case 0 -> trySimplifyNullaryMethod(methodInvocation, state);
+      case 1 -> trySimplifyUnaryMethod(methodInvocation, state);
+      default ->
+          throw new IllegalStateException(
+              "Cannot simplify method call with two or more arguments: "
+                  + SourceCode.treeToString(tree, state));
+    };
   }
 
   private static Optional<ExpressionTree> trySimplifyNullaryMethod(
       MethodInvocationTree methodInvocation, VisitorState state) {
-    if (!instanceMethod().matches(methodInvocation, state)) {
+    if (!instanceMethod().matches(methodInvocation, state)
+        || !(methodInvocation.getMethodSelect() instanceof MemberSelectTree memberSelect)) {
       return Optional.empty();
     }
 
-    return Optional.of(methodInvocation.getMethodSelect())
-        .filter(methodSelect -> methodSelect.getKind() == Kind.MEMBER_SELECT)
-        .map(methodSelect -> ((MemberSelectTree) methodSelect).getExpression())
+    return Optional.of(memberSelect.getExpression())
         .filter(expr -> !"super".equals(SourceCode.treeToString(expr, state)));
   }
 
@@ -378,11 +378,11 @@ public final class RedundantStringConversion extends BugChecker
 
   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/RequestMappingAnnotation.java

@@ -11,7 +11,7 @@ import static com.google.errorprone.matchers.Matchers.isSameType;
 import static com.google.errorprone.matchers.Matchers.isType;
 import static com.google.errorprone.matchers.Matchers.methodHasParameters;
 import static com.google.errorprone.matchers.Matchers.not;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
 import com.google.errorprone.BugPattern;
@@ -22,6 +22,10 @@ import com.google.errorprone.matchers.Description;
 import com.google.errorprone.matchers.Matcher;
 import com.sun.source.tree.MethodTree;
 import com.sun.source.tree.Tree;
+import java.io.InputStream;
+import java.time.ZoneId;
+import java.util.Locale;
+import java.util.TimeZone;
 
 /**
  * A {@link BugChecker} that flags {@code @RequestMapping} methods that have one or more parameters
@@ -69,11 +73,13 @@ public final class RequestMappingAnnotation extends BugChecker implements Method
                           isType(ANN_PACKAGE_PREFIX + "RequestBody"),
                           isType(ANN_PACKAGE_PREFIX + "RequestHeader"),
                           isType(ANN_PACKAGE_PREFIX + "RequestParam"),
-                          isType(ANN_PACKAGE_PREFIX + "RequestPart"))),
-                  isSameType("java.io.InputStream"),
-                  isSameType("java.time.ZoneId"),
-                  isSameType("java.util.Locale"),
-                  isSameType("java.util.TimeZone"),
+                          isType(ANN_PACKAGE_PREFIX + "RequestPart"),
+                          isType(
+                              "org.springframework.security.core.annotation.CurrentSecurityContext"))),
+                  isSameType(InputStream.class.getCanonicalName()),
+                  isSameType(Locale.class.getCanonicalName()),
+                  isSameType(TimeZone.class.getCanonicalName()),
+                  isSameType(ZoneId.class.getCanonicalName()),
                   isSameType("jakarta.servlet.http.HttpServletRequest"),
                   isSameType("jakarta.servlet.http.HttpServletResponse"),
                   isSameType("javax.servlet.http.HttpServletRequest"),
@@ -99,9 +105,10 @@ public final class RequestMappingAnnotation extends BugChecker implements Method
             && LACKS_PARAMETER_ANNOTATION.matches(tree, state)
         ? buildDescription(tree)
             .setMessage(
-                "Not all parameters of this request mapping method are annotated; this may be a "
-                    + "mistake. If the unannotated parameters represent query string parameters, "
-                    + "annotate them with `@RequestParam`.")
+                """
+                Not all parameters of this request mapping method are annotated; this may be a \
+                mistake. If the unannotated parameters represent query string parameters, annotate \
+                them with `@RequestParam`.""")
             .build()
         : Description.NO_MATCH;
   }

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

@@ -11,12 +11,12 @@ import static com.google.errorprone.matchers.Matchers.anyOf;
 import static com.google.errorprone.matchers.Matchers.isSubtypeOf;
 import static com.google.errorprone.matchers.Matchers.isType;
 import static com.google.errorprone.matchers.Matchers.not;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+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;
@@ -28,13 +28,15 @@ import com.google.errorprone.suppliers.Suppliers;
 import com.sun.source.tree.Tree;
 import com.sun.source.tree.VariableTree;
 import javax.inject.Inject;
-import tech.picnic.errorprone.bugpatterns.util.Flags;
+import tech.picnic.errorprone.utils.Flags;
 
 /** A {@link BugChecker} that flags {@code @RequestParam} parameters with an unsupported type. */
 @AutoService(BugChecker.class)
 @BugPattern(
     summary =
-        "By default, `@RequestParam` does not support `ImmutableCollection` and `ImmutableMap` subtypes",
+        """
+        By default, `@RequestParam` does not support `ImmutableCollection` and `ImmutableMap` \
+        subtypes""",
     link = BUG_PATTERNS_BASE_URL + "RequestParamType",
     linkType = CUSTOM,
     severity = ERROR,
@@ -72,10 +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

@@ -6,7 +6,7 @@ import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
 import static com.google.errorprone.BugPattern.StandardTags.LIKELY_ERROR;
 import static com.google.errorprone.matchers.Matchers.isSubtypeOf;
 import static com.google.errorprone.matchers.method.MethodMatchers.instanceMethod;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
 import com.google.common.base.Splitter;
@@ -23,13 +23,11 @@ import com.sun.source.tree.MethodInvocationTree;
 import com.sun.source.tree.Tree.Kind;
 import java.util.List;
 import java.util.Optional;
-import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+import tech.picnic.errorprone.utils.SourceCode;
 
 /** A {@link BugChecker} that flags SLF4J usages that are likely to be in error. */
 // XXX: The special-casing of Throwable applies only to SLF4J 1.6.0+; see
 // https://www.slf4j.org/faq.html#paramException. That should be documented.
-// XXX: Also simplify `LOG.error(String.format("Something %s", arg), throwable)`.
-// XXX: Also simplify `LOG.error(String.join("sep", arg1, arg2), throwable)`? Perhaps too obscure.
 // XXX: Write a similar checker for Spring RestTemplates, String.format and friends, Guava
 // preconditions, ...
 @AutoService(BugChecker.class)
@@ -41,7 +39,7 @@ import tech.picnic.errorprone.bugpatterns.util.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 +69,7 @@ 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

@@ -1,12 +1,11 @@
 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.SUGGESTION;
 import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
 import static java.util.function.Predicate.not;
 import static java.util.stream.Collectors.joining;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
 import com.google.common.base.VerifyException;
@@ -18,16 +17,16 @@ 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;
 import com.sun.source.tree.AnnotationTree;
 import com.sun.source.tree.AssignmentTree;
 import com.sun.source.tree.ExpressionTree;
 import com.sun.source.tree.MemberSelectTree;
 import com.sun.source.tree.NewArrayTree;
-import com.sun.source.tree.Tree.Kind;
 import java.util.Optional;
-import tech.picnic.errorprone.bugpatterns.util.AnnotationAttributeMatcher;
-import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+import tech.picnic.errorprone.utils.AnnotationAttributeMatcher;
+import tech.picnic.errorprone.utils.SourceCode;
 
 /**
  * A {@link BugChecker} that flags {@code @RequestMapping} annotations that can be written more
@@ -55,7 +54,7 @@ public final class SpringMvcAnnotation extends BugChecker implements AnnotationT
           .put("PATCH", "PatchMapping")
           .put("POST", "PostMapping")
           .put("PUT", "PutMapping")
-          .build();
+          .buildOrThrow();
 
   /** Instantiates a new {@link SpringMvcAnnotation} instance. */
   public SpringMvcAnnotation() {}
@@ -79,31 +78,25 @@ public final class SpringMvcAnnotation extends BugChecker implements AnnotationT
   }
 
   private static Optional<String> extractUniqueMethod(ExpressionTree arg, VisitorState state) {
-    verify(
-        arg.getKind() == Kind.ASSIGNMENT,
-        "Annotation attribute is not an assignment: %s",
-        arg.getKind());
-
-    ExpressionTree expr = ((AssignmentTree) arg).getExpression();
-    if (expr.getKind() != Kind.NEW_ARRAY) {
-      return Optional.of(extractMethod(expr, state));
+    if (!(arg instanceof AssignmentTree assignment)) {
+      throw new VerifyException("Annotation attribute is not an assignment:" + arg.getKind());
     }
 
-    NewArrayTree newArray = (NewArrayTree) expr;
-    return Optional.of(newArray.getInitializers())
-        .filter(args -> args.size() == 1)
-        .map(args -> extractMethod(args.get(0), state));
+    ExpressionTree expr = assignment.getExpression();
+    return expr instanceof NewArrayTree newArray
+        ? Optional.of(newArray.getInitializers())
+            .filter(args -> args.size() == 1)
+            .map(args -> extractMethod(args.get(0), state))
+        : Optional.of(extractMethod(expr, state));
   }
 
+  // XXX: Use switch pattern matching once the targeted JDK supports this.
   private static String extractMethod(ExpressionTree expr, VisitorState state) {
-    switch (expr.getKind()) {
-      case IDENTIFIER:
-        return SourceCode.treeToString(expr, state);
-      case MEMBER_SELECT:
-        return ((MemberSelectTree) expr).getIdentifier().toString();
-      default:
-        throw new VerifyException("Unexpected type of expression: " + expr.getKind());
-    }
+    return switch (expr.getKind()) {
+      case IDENTIFIER -> SourceCode.treeToString(expr, state);
+      case MEMBER_SELECT -> ((MemberSelectTree) expr).getIdentifier().toString();
+      default -> throw new VerifyException("Unexpected type of expression: " + expr.getKind());
+    };
   }
 
   private static Fix replaceAnnotation(
@@ -114,9 +107,8 @@ public final class SpringMvcAnnotation extends BugChecker implements AnnotationT
             .map(arg -> SourceCode.treeToString(arg, state))
             .collect(joining(", "));
 
-    return SuggestedFix.builder()
-        .addImport(ANN_PACKAGE_PREFIX + newAnnotation)
-        .replace(tree, String.format("@%s(%s)", newAnnotation, newArguments))
-        .build();
+    SuggestedFix.Builder fix = SuggestedFix.builder();
+    String annotation = SuggestedFixes.qualifyType(state, fix, ANN_PACKAGE_PREFIX + newAnnotation);
+    return fix.replace(tree, String.format("@%s(%s)", annotation, newArguments)).build();
   }
 }

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

@@ -6,12 +6,28 @@ import static com.google.errorprone.BugPattern.StandardTags.STYLE;
 import static java.util.Objects.requireNonNull;
 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.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Functions;
+import com.google.common.base.Preconditions;
+import com.google.common.base.Predicates;
+import com.google.common.base.Verify;
+import com.google.common.collect.Comparators;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableListMultimap;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableMultiset;
+import com.google.common.collect.ImmutableRangeSet;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.ImmutableSetMultimap;
+import com.google.common.collect.ImmutableSortedMap;
+import com.google.common.collect.ImmutableSortedMultiset;
+import com.google.common.collect.ImmutableSortedSet;
+import com.google.common.collect.ImmutableTable;
+import com.google.common.collect.MoreCollectors;
+import com.google.common.collect.Sets;
 import com.google.errorprone.BugPattern;
 import com.google.errorprone.VisitorState;
 import com.google.errorprone.bugpatterns.BugChecker;
@@ -22,12 +38,27 @@ import com.google.errorprone.fixes.Fix;
 import com.google.errorprone.fixes.SuggestedFix;
 import com.google.errorprone.fixes.SuggestedFixes;
 import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matchers;
+import com.google.errorprone.predicates.TypePredicates;
+import com.google.errorprone.refaster.ImportPolicy;
 import com.google.errorprone.util.ASTHelpers;
 import com.sun.source.tree.MemberSelectTree;
 import com.sun.source.tree.MethodInvocationTree;
 import com.sun.source.tree.Tree;
+import com.sun.source.tree.Tree.Kind;
 import com.sun.tools.javac.code.Type;
+import java.nio.charset.StandardCharsets;
+import java.time.ZoneOffset;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.Map;
+import java.util.Objects;
 import java.util.Optional;
+import java.util.UUID;
+import java.util.function.Function;
+import java.util.function.Predicate;
+import java.util.regex.Pattern;
+import java.util.stream.Collectors;
 
 /** A {@link BugChecker} that flags type members that can and should be statically imported. */
 // XXX: This check is closely linked to `NonStaticImport`. Consider merging the two.
@@ -57,15 +88,26 @@ public final class StaticImport extends BugChecker implements MemberSelectTreeMa
   @VisibleForTesting
   static final ImmutableSet<String> STATIC_IMPORT_CANDIDATE_TYPES =
       ImmutableSet.of(
-          "com.google.common.base.Preconditions",
-          "com.google.common.base.Predicates",
-          "com.google.common.base.Verify",
-          "com.google.common.collect.MoreCollectors",
-          "com.google.errorprone.BugPattern.LinkType",
-          "com.google.errorprone.BugPattern.SeverityLevel",
-          "com.google.errorprone.BugPattern.StandardTags",
-          "com.google.errorprone.matchers.Matchers",
-          "com.google.errorprone.refaster.ImportPolicy",
+          BugPattern.LinkType.class.getCanonicalName(),
+          BugPattern.SeverityLevel.class.getCanonicalName(),
+          BugPattern.StandardTags.class.getCanonicalName(),
+          Collections.class.getCanonicalName(),
+          Collectors.class.getCanonicalName(),
+          Comparator.class.getCanonicalName(),
+          ImportPolicy.class.getCanonicalName(),
+          Map.Entry.class.getCanonicalName(),
+          Matchers.class.getCanonicalName(),
+          MoreCollectors.class.getCanonicalName(),
+          Pattern.class.getCanonicalName(),
+          Preconditions.class.getCanonicalName(),
+          Predicates.class.getCanonicalName(),
+          StandardCharsets.class.getCanonicalName(),
+          TypePredicates.class.getCanonicalName(),
+          Verify.class.getCanonicalName(),
+          "com.fasterxml.jackson.annotation.JsonCreator.Mode",
+          "com.fasterxml.jackson.annotation.JsonFormat.Shape",
+          "com.fasterxml.jackson.annotation.JsonInclude.Include",
+          "com.fasterxml.jackson.annotation.JsonProperty.Access",
           "com.mongodb.client.model.Accumulators",
           "com.mongodb.client.model.Aggregates",
           "com.mongodb.client.model.Filters",
@@ -73,12 +115,6 @@ public final class StaticImport extends BugChecker implements MemberSelectTreeMa
           "com.mongodb.client.model.Projections",
           "com.mongodb.client.model.Sorts",
           "com.mongodb.client.model.Updates",
-          "java.nio.charset.StandardCharsets",
-          "java.util.Collections",
-          "java.util.Comparator",
-          "java.util.Map.Entry",
-          "java.util.regex.Pattern",
-          "java.util.stream.Collectors",
           "org.assertj.core.api.Assertions",
           "org.assertj.core.api.InstanceOfAssertFactories",
           "org.assertj.core.api.SoftAssertions",
@@ -99,7 +135,7 @@ public final class StaticImport extends BugChecker implements MemberSelectTreeMa
           "org.springframework.http.MediaType",
           "org.testng.Assert",
           "reactor.function.TupleUtils",
-          "tech.picnic.errorprone.bugpatterns.util.MoreTypes");
+          "tech.picnic.errorprone.utils.MoreTypes");
 
   /**
    * Type members that should be statically imported.
@@ -117,39 +153,39 @@ public final class StaticImport extends BugChecker implements MemberSelectTreeMa
    */
   static final ImmutableSetMultimap<String, String> STATIC_IMPORT_CANDIDATE_MEMBERS =
       ImmutableSetMultimap.<String, String>builder()
+          .putAll(Comparators.class.getCanonicalName(), "emptiesFirst", "emptiesLast")
+          .put(Function.class.getCanonicalName(), "identity")
+          .put(Functions.class.getCanonicalName(), "identity")
+          .put(ImmutableList.class.getCanonicalName(), "toImmutableList")
           .putAll(
-              "com.google.common.collect.ImmutableListMultimap",
+              ImmutableListMultimap.class.getCanonicalName(),
               "flatteningToImmutableListMultimap",
               "toImmutableListMultimap")
-          .put("com.google.common.collect.ImmutableList", "toImmutableList")
-          .put("com.google.common.collect.ImmutableMap", "toImmutableMap")
-          .put("com.google.common.collect.ImmutableMultiset", "toImmutableMultiset")
-          .put("com.google.common.collect.ImmutableRangeSet", "toImmutableRangeSet")
+          .put(ImmutableMap.class.getCanonicalName(), "toImmutableMap")
+          .put(ImmutableMultiset.class.getCanonicalName(), "toImmutableMultiset")
+          .put(ImmutableRangeSet.class.getCanonicalName(), "toImmutableRangeSet")
+          .put(ImmutableSet.class.getCanonicalName(), "toImmutableSet")
           .putAll(
-              "com.google.common.collect.ImmutableSetMultimap",
+              ImmutableSetMultimap.class.getCanonicalName(),
               "flatteningToImmutableSetMultimap",
               "toImmutableSetMultimap")
-          .put("com.google.common.collect.ImmutableSet", "toImmutableSet")
-          .put("com.google.common.collect.ImmutableSortedMap", "toImmutableSortedMap")
-          .put("com.google.common.collect.ImmutableSortedMultiset", "toImmutableSortedMultiset")
-          .put("com.google.common.collect.ImmutableSortedSet", "toImmutableSortedSet")
-          .put("com.google.common.collect.ImmutableTable", "toImmutableTable")
-          .put("com.google.common.collect.Sets", "toImmutableEnumSet")
-          .put("com.google.common.base.Functions", "identity")
-          .put("java.time.ZoneOffset", "UTC")
-          .put("java.util.function.Function", "identity")
-          .put("java.util.function.Predicate", "not")
-          .put("java.util.UUID", "randomUUID")
-          .put("org.junit.jupiter.params.provider.Arguments", "arguments")
+          .put(ImmutableSortedMap.class.getCanonicalName(), "toImmutableSortedMap")
+          .put(ImmutableSortedMultiset.class.getCanonicalName(), "toImmutableSortedMultiset")
+          .put(ImmutableSortedSet.class.getCanonicalName(), "toImmutableSortedSet")
+          .put(ImmutableTable.class.getCanonicalName(), "toImmutableTable")
           .putAll(
-              "java.util.Objects",
+              Objects.class.getCanonicalName(),
               "checkIndex",
               "checkFromIndexSize",
               "checkFromToIndex",
               "requireNonNull",
               "requireNonNullElse",
               "requireNonNullElseGet")
-          .putAll("com.google.common.collect.Comparators", "emptiesFirst", "emptiesLast")
+          .put(Predicate.class.getCanonicalName(), "not")
+          .put(Sets.class.getCanonicalName(), "toImmutableEnumSet")
+          .put(UUID.class.getCanonicalName(), "randomUUID")
+          .put(ZoneOffset.class.getCanonicalName(), "UTC")
+          .put("org.junit.jupiter.params.provider.Arguments", "arguments")
           .build();
 
   /** Instantiates a new {@link StaticImport} instance. */
@@ -176,15 +212,10 @@ public final class StaticImport extends BugChecker implements MemberSelectTreeMa
     Tree parentTree =
         requireNonNull(state.getPath().getParentPath(), "MemberSelectTree lacks enclosing node")
             .getLeaf();
-    switch (parentTree.getKind()) {
-      case IMPORT:
-      case MEMBER_SELECT:
-        return false;
-      case METHOD_INVOCATION:
-        return ((MethodInvocationTree) parentTree).getTypeArguments().isEmpty();
-      default:
-        return true;
-    }
+
+    return parentTree instanceof MethodInvocationTree methodInvocation
+        ? methodInvocation.getTypeArguments().isEmpty()
+        : (parentTree.getKind() != Kind.IMPORT && parentTree.getKind() != Kind.MEMBER_SELECT);
   }
 
   private static boolean isCandidate(MemberSelectTree tree) {

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

@@ -4,7 +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.SIMPLIFICATION;
 import static com.google.errorprone.matchers.method.MethodMatchers.staticMethod;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
 import com.google.common.base.Splitter;
@@ -23,12 +23,11 @@ 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;
 import org.jspecify.annotations.Nullable;
-import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+import tech.picnic.errorprone.utils.SourceCode;
 
 /**
  * A {@link BugChecker} that flags {@link String#format(String, Object...)} invocations which can be
@@ -37,7 +36,9 @@ import tech.picnic.errorprone.bugpatterns.util.SourceCode;
  */
 // XXX: What about `v1 + "sep" + v2` and similar expressions? Do we want to rewrite those to
 // `String.join`, or should some `String.join` invocations be rewritten to use the `+` operator?
-// (The latter suggestion would conflict with the `FormatStringConcatenation` check.)
+// (The latter suggestion would conflict with the `FormatStringConcatenation` check, but does make
+// more sense when `"sep"` is a long string. Similarly for `String.format("%s some long text %s",
+// arg1, arg2)`.)
 @AutoService(BugChecker.class)
 @BugPattern(
     summary = "Prefer `String#join` over `String#format`",
@@ -49,7 +50,7 @@ public final class StringJoin extends BugChecker implements MethodInvocationTree
   private static final long serialVersionUID = 1L;
   private static final Splitter FORMAT_SPECIFIER_SPLITTER = Splitter.on("%s");
   private static final Matcher<ExpressionTree> STRING_FORMAT_INVOCATION =
-      staticMethod().onClass(String.class.getName()).named("format");
+      staticMethod().onClass(String.class.getCanonicalName()).named("format");
   private static final Supplier<Type> CHAR_SEQUENCE_TYPE =
       Suppliers.typeFromClass(CharSequence.class);
   private static final Supplier<Type> FORMATTABLE_TYPE = Suppliers.typeFromClass(Formattable.class);
@@ -150,7 +151,7 @@ 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/bugpatterns/TimeZoneUsage.java

@@ -10,16 +10,18 @@ import static com.google.errorprone.matchers.Matchers.instanceMethod;
 import static com.google.errorprone.matchers.Matchers.isSubtypeOf;
 import static com.google.errorprone.matchers.Matchers.not;
 import static com.google.errorprone.matchers.Matchers.staticMethod;
-import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+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.MemberReferenceTreeMatcher;
 import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
 import com.google.errorprone.matchers.Description;
 import com.google.errorprone.matchers.Matcher;
 import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.MemberReferenceTree;
 import com.sun.source.tree.MethodInvocationTree;
 import java.time.Clock;
 import java.time.Instant;
@@ -34,22 +36,25 @@ import java.time.ZonedDateTime;
 @AutoService(BugChecker.class)
 @BugPattern(
     summary =
-        "Derive the current time from an existing `Clock` Spring bean, and don't rely on a `Clock`'s time zone",
+        """
+        Derive the current time from an existing `Clock` Spring bean, and don't rely on a \
+        `Clock`'s time zone""",
     link = BUG_PATTERNS_BASE_URL + "TimeZoneUsage",
     linkType = CUSTOM,
     severity = WARNING,
     tags = FRAGILE_CODE)
-public final class TimeZoneUsage extends BugChecker implements MethodInvocationTreeMatcher {
+public final class TimeZoneUsage extends BugChecker
+    implements MethodInvocationTreeMatcher, MemberReferenceTreeMatcher {
   private static final long serialVersionUID = 1L;
   private static final Matcher<ExpressionTree> BANNED_TIME_METHOD =
       anyOf(
           allOf(
               instanceMethod()
-                  .onDescendantOf(Clock.class.getName())
+                  .onDescendantOf(Clock.class.getCanonicalName())
                   .namedAnyOf("getZone", "withZone"),
               not(enclosingClass(isSubtypeOf(Clock.class)))),
           staticMethod()
-              .onClass(Clock.class.getName())
+              .onClass(Clock.class.getCanonicalName())
               .namedAnyOf(
                   "system",
                   "systemDefaultZone",
@@ -57,22 +62,34 @@ public final class TimeZoneUsage extends BugChecker implements MethodInvocationT
                   "tickMillis",
                   "tickMinutes",
                   "tickSeconds"),
+          staticMethod()
+              .onClassAny(Instant.class.getCanonicalName())
+              .named("now")
+              .withNoParameters(),
           staticMethod()
               .onClassAny(
-                  LocalDate.class.getName(),
-                  LocalDateTime.class.getName(),
-                  LocalTime.class.getName(),
-                  OffsetDateTime.class.getName(),
-                  OffsetTime.class.getName(),
-                  ZonedDateTime.class.getName())
-              .named("now"),
-          staticMethod().onClassAny(Instant.class.getName()).named("now").withNoParameters());
+                  LocalDate.class.getCanonicalName(),
+                  LocalDateTime.class.getCanonicalName(),
+                  LocalTime.class.getCanonicalName(),
+                  OffsetDateTime.class.getCanonicalName(),
+                  OffsetTime.class.getCanonicalName(),
+                  ZonedDateTime.class.getCanonicalName())
+              .named("now"));
 
   /** Instantiates a new {@link TimeZoneUsage} instance. */
   public TimeZoneUsage() {}
 
   @Override
   public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    return getDescription(tree, state);
+  }
+
+  @Override
+  public Description matchMemberReference(MemberReferenceTree tree, VisitorState state) {
+    return getDescription(tree, state);
+  }
+
+  private Description getDescription(ExpressionTree tree, VisitorState state) {
     return BANNED_TIME_METHOD.matches(tree, state)
         ? buildDescription(tree).build()
         : Description.NO_MATCH;

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

@@ -1,75 +0,0 @@
-package tech.picnic.errorprone.bugpatterns.util;
-
-import static tech.picnic.errorprone.bugpatterns.util.JavaKeywords.isValidIdentifier;
-
-import com.google.errorprone.VisitorState;
-import com.google.errorprone.util.ASTHelpers;
-import com.sun.source.tree.ImportTree;
-import com.sun.source.tree.Tree;
-import com.sun.tools.javac.code.Symbol.MethodSymbol;
-import com.sun.tools.javac.code.Type;
-import java.util.Optional;
-
-/** A set of helper methods for detecting conflicts that would be caused when applying fixes. */
-public final class ConflictDetection {
-  private ConflictDetection() {}
-
-  /**
-   * If applicable, returns a human-readable argument against assigning the given name to an
-   * existing method.
-   *
-   * <p>This method implements imperfect heuristics. Things it currently does not consider include
-   * the following:
-   *
-   * <ul>
-   *   <li>Whether the rename would merely introduce a method overload, rather than clashing with an
-   *       existing method declaration in its class or a supertype.
-   *   <li>Whether the rename would in fact clash with a static import. (It could be that a static
-   *       import of the same name is only referenced from lexical scopes in which the method under
-   *       consideration cannot be referenced directly.)
-   * </ul>
-   *
-   * @param method The method considered for renaming.
-   * @param newName The newly proposed name for the method.
-   * @param state The {@link VisitorState} to use when searching for blockers.
-   * @return A human-readable argument against assigning the proposed name to the given method, or
-   *     {@link Optional#empty()} if no blocker was found.
-   */
-  public static Optional<String> findMethodRenameBlocker(
-      MethodSymbol method, String newName, VisitorState state) {
-    if (isExistingMethodName(method.owner.type, newName, state)) {
-      return Optional.of(
-          String.format(
-              "a method named `%s` is already defined in this class or a supertype", newName));
-    }
-
-    if (isSimpleNameStaticallyImported(newName, state)) {
-      return Optional.of(String.format("`%s` is already statically imported", newName));
-    }
-
-    if (!isValidIdentifier(newName)) {
-      return Optional.of(String.format("`%s` is not a valid identifier", newName));
-    }
-
-    return Optional.empty();
-  }
-
-  private static boolean isExistingMethodName(Type clazz, String name, VisitorState state) {
-    return ASTHelpers.matchingMethods(state.getName(name), method -> true, clazz, state.getTypes())
-        .findAny()
-        .isPresent();
-  }
-
-  private static boolean isSimpleNameStaticallyImported(String simpleName, VisitorState state) {
-    return state.getPath().getCompilationUnit().getImports().stream()
-        .filter(ImportTree::isStatic)
-        .map(ImportTree::getQualifiedIdentifier)
-        .map(tree -> getStaticImportSimpleName(tree, state))
-        .anyMatch(simpleName::contentEquals);
-  }
-
-  private static CharSequence getStaticImportSimpleName(Tree tree, VisitorState state) {
-    String source = SourceCode.treeToString(tree, state);
-    return source.subSequence(source.lastIndexOf('.') + 1, source.length());
-  }
-}

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

@@ -1,22 +0,0 @@
-package tech.picnic.errorprone.bugpatterns.util;
-
-import com.google.common.collect.ImmutableList;
-import com.google.errorprone.ErrorProneFlags;
-
-/** Helper methods for working with {@link ErrorProneFlags}. */
-public final class Flags {
-  private Flags() {}
-
-  /**
-   * Returns the list 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} list of provided arguments; this list is empty if the flag was not
-   *     provided, or if the flag's value is the empty string.
-   */
-  public static ImmutableList<String> getList(ErrorProneFlags errorProneFlags, String name) {
-    ImmutableList<String> list = errorProneFlags.getListOrEmpty(name);
-    return list.equals(ImmutableList.of("")) ? ImmutableList.of() : list;
-  }
-}

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

@@ -1,159 +0,0 @@
-package tech.picnic.errorprone.bugpatterns.util;
-
-import com.google.common.collect.ImmutableSet;
-import com.google.common.collect.Sets;
-
-/** Utility class that can be used to identify reserved keywords of the Java language. */
-// XXX: This class is no longer only about keywords. Consider changing its name and class-level
-// documentation.
-public final class JavaKeywords {
-  /**
-   * Enumeration of boolean and null literals.
-   *
-   * @see <a href="https://docs.oracle.com/javase/specs/jls/se17/html/jls-3.html#jls-3.10.3">JDK 17
-   *     JLS section 3.10.3: Boolean Literals</a>
-   * @see <a href="https://docs.oracle.com/javase/specs/jls/se17/html/jls-3.html#jls-3.10.8">JDK 17
-   *     JLS section 3.10.8: The Null Literal</a>
-   */
-  private static final ImmutableSet<String> BOOLEAN_AND_NULL_LITERALS =
-      ImmutableSet.of("true", "false", "null");
-
-  /**
-   * List of all reserved keywords in the Java language.
-   *
-   * @see <a href="https://docs.oracle.com/javase/specs/jls/se17/html/jls-3.html#jls-3.9">JDK 17 JLS
-   *     section 3.9: Keywords</a>
-   */
-  private static final ImmutableSet<String> RESERVED_KEYWORDS =
-      ImmutableSet.of(
-          "_",
-          "abstract",
-          "assert",
-          "boolean",
-          "break",
-          "byte",
-          "case",
-          "catch",
-          "char",
-          "class",
-          "const",
-          "continue",
-          "default",
-          "do",
-          "double",
-          "else",
-          "enum",
-          "extends",
-          "final",
-          "finally",
-          "float",
-          "for",
-          "goto",
-          "if",
-          "implements",
-          "import",
-          "instanceof",
-          "int",
-          "interface",
-          "long",
-          "native",
-          "new",
-          "package",
-          "private",
-          "protected",
-          "public",
-          "return",
-          "short",
-          "static",
-          "strictfp",
-          "super",
-          "switch",
-          "synchronized",
-          "this",
-          "throw",
-          "throws",
-          "transient",
-          "try",
-          "void",
-          "volatile",
-          "while");
-
-  /**
-   * List of all contextual keywords in the Java language.
-   *
-   * @see <a href="https://docs.oracle.com/javase/specs/jls/se17/html/jls-3.html#jls-3.9">JDK 17 JLS
-   *     section 3.9: Keywords</a>
-   */
-  private static final ImmutableSet<String> CONTEXTUAL_KEYWORDS =
-      ImmutableSet.of(
-          "exports",
-          "module",
-          "non-sealed",
-          "open",
-          "opens",
-          "permits",
-          "provides",
-          "record",
-          "requires",
-          "sealed",
-          "to",
-          "transitive",
-          "uses",
-          "var",
-          "with",
-          "yield");
-
-  /** List of all keywords in the Java language. */
-  private static final ImmutableSet<String> ALL_KEYWORDS =
-      Sets.union(RESERVED_KEYWORDS, CONTEXTUAL_KEYWORDS).immutableCopy();
-
-  private JavaKeywords() {}
-
-  /**
-   * Tells whether the given string is a valid identifier in the Java language.
-   *
-   * @param str The string of interest.
-   * @return {@code true} if the given string is a valid identifier in the Java language.
-   * @see <a href="https://docs.oracle.com/javase/specs/jls/se17/html/jls-3.html#jls-3.8">JDK 17 JLS
-   *     section 3.8: Identifiers</a>
-   */
-  @SuppressWarnings("java:S1067" /* Chaining conjunctions like this does not impact readability. */)
-  public static boolean isValidIdentifier(String str) {
-    return !str.isEmpty()
-        && !isReservedKeyword(str)
-        && !BOOLEAN_AND_NULL_LITERALS.contains(str)
-        && Character.isJavaIdentifierStart(str.codePointAt(0))
-        && str.codePoints().skip(1).allMatch(Character::isUnicodeIdentifierPart);
-  }
-
-  /**
-   * Tells whether the given string is a reserved keyword in the Java language.
-   *
-   * @param str The string of interest.
-   * @return {@code true} if the given string is a reserved keyword in the Java language.
-   */
-  public static boolean isReservedKeyword(String str) {
-    return RESERVED_KEYWORDS.contains(str);
-  }
-
-  /**
-   * Tells whether the given string is a contextual keyword in the Java language.
-   *
-   * @param str The string of interest.
-   * @return {@code true} if the given string is a contextual keyword in the Java language.
-   */
-  public static boolean isContextualKeyword(String str) {
-    return CONTEXTUAL_KEYWORDS.contains(str);
-  }
-
-  /**
-   * Tells whether the given string is a reserved or contextual keyword in the Java language.
-   *
-   * @param str The string of interest.
-   * @return {@code true} if the given string is a reserved or contextual keyword in the Java
-   *     language.
-   */
-  public static boolean isKeyword(String str) {
-    return ALL_KEYWORDS.contains(str);
-  }
-}

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

@@ -18,6 +18,7 @@ final class AssertJCharSequenceRules {
     @BeforeTemplate
     void before(CharSequence charSequence) {
       Refaster.anyOf(
+          assertThat(charSequence.isEmpty()).isTrue(),
           assertThat(charSequence.length()).isEqualTo(0L),
           assertThat(charSequence.length()).isNotPositive());
     }
@@ -33,6 +34,7 @@ final class AssertJCharSequenceRules {
     @BeforeTemplate
     AbstractAssert<?, ?> before(CharSequence charSequence) {
       return Refaster.anyOf(
+          assertThat(charSequence.isEmpty()).isFalse(),
           assertThat(charSequence.length()).isNotEqualTo(0),
           assertThat(charSequence.length()).isPositive());
     }

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

@@ -5,6 +5,9 @@ import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import java.util.Collection;
+import org.assertj.core.api.AbstractIntegerAssert;
+import org.assertj.core.api.AbstractIterableAssert;
+import org.assertj.core.api.AbstractIterableSizeAssert;
 import org.assertj.core.api.EnumerableAssert;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 
@@ -21,6 +24,11 @@ final class AssertJEnumerableRules {
           enumAssert.hasSizeLessThan(1));
     }
 
+    @BeforeTemplate
+    void before(AbstractIterableAssert<?, ?, E, ?> enumAssert) {
+      enumAssert.size().isNotPositive();
+    }
+
     @AfterTemplate
     void after(EnumerableAssert<?, E> enumAssert) {
       enumAssert.isEmpty();
@@ -34,30 +42,170 @@ final class AssertJEnumerableRules {
           enumAssert.hasSizeGreaterThan(0), enumAssert.hasSizeGreaterThanOrEqualTo(1));
     }
 
+    @BeforeTemplate
+    AbstractIterableAssert<?, ?, E, ?> before(AbstractIterableAssert<?, ?, E, ?> enumAssert) {
+      return Refaster.anyOf(
+          enumAssert.size().isNotEqualTo(0).returnToIterable(),
+          enumAssert.size().isPositive().returnToIterable());
+    }
+
+    // XXX: If this template matches, then the expression's return type changes incompatibly.
+    // Consider moving this template to a separate block (statement) rule.
+    @BeforeTemplate
+    AbstractIntegerAssert<?> before2(AbstractIterableAssert<?, ?, E, ?> enumAssert) {
+      return Refaster.anyOf(enumAssert.size().isNotEqualTo(0), enumAssert.size().isPositive());
+    }
+
     @AfterTemplate
     EnumerableAssert<?, E> after(EnumerableAssert<?, E> enumAssert) {
       return enumAssert.isNotEmpty();
     }
   }
 
-  static final class EnumerableAssertHasSameSizeAs<S, T> {
+  static final class EnumerableAssertHasSize<E> {
     @BeforeTemplate
-    EnumerableAssert<?, S> before(EnumerableAssert<?, S> enumAssert, Iterable<T> iterable) {
+    AbstractIterableAssert<?, ?, E, ?> before(
+        AbstractIterableAssert<?, ?, E, ?> enumAssert, int size) {
+      return enumAssert.size().isEqualTo(size).returnToIterable();
+    }
+
+    // XXX: If this template matches, then the expression's return type changes incompatibly.
+    // Consider moving this template to a separate block (statement) rule.
+    @BeforeTemplate
+    AbstractIterableSizeAssert<?, ?, E, ?> before2(
+        AbstractIterableAssert<?, ?, E, ?> enumAssert, int size) {
+      return enumAssert.size().isEqualTo(size);
+    }
+
+    @AfterTemplate
+    EnumerableAssert<?, E> after(EnumerableAssert<?, E> enumAssert, int size) {
+      return enumAssert.hasSize(size);
+    }
+  }
+
+  static final class EnumerableAssertHasSizeLessThan<E> {
+    @BeforeTemplate
+    AbstractIterableAssert<?, ?, E, ?> before(
+        AbstractIterableAssert<?, ?, E, ?> enumAssert, int size) {
+      return enumAssert.size().isLessThan(size).returnToIterable();
+    }
+
+    // XXX: If this template matches, then the expression's return type changes incompatibly.
+    // Consider moving this template to a separate block (statement) rule.
+    @BeforeTemplate
+    AbstractIterableSizeAssert<?, ?, E, ?> before2(
+        AbstractIterableAssert<?, ?, E, ?> enumAssert, int size) {
+      return enumAssert.size().isLessThan(size);
+    }
+
+    @AfterTemplate
+    EnumerableAssert<?, E> after(EnumerableAssert<?, E> enumAssert, int size) {
+      return enumAssert.hasSizeLessThan(size);
+    }
+  }
+
+  static final class EnumerableAssertHasSizeLessThanOrEqualTo<E> {
+    @BeforeTemplate
+    AbstractIterableAssert<?, ?, E, ?> before(
+        AbstractIterableAssert<?, ?, E, ?> enumAssert, int size) {
+      return enumAssert.size().isLessThanOrEqualTo(size).returnToIterable();
+    }
+
+    // XXX: If this template matches, then the expression's return type changes incompatibly.
+    // Consider moving this template to a separate block (statement) rule.
+    @BeforeTemplate
+    AbstractIterableSizeAssert<?, ?, E, ?> before2(
+        AbstractIterableAssert<?, ?, E, ?> enumAssert, int size) {
+      return enumAssert.size().isLessThanOrEqualTo(size);
+    }
+
+    @AfterTemplate
+    EnumerableAssert<?, E> after(EnumerableAssert<?, E> enumAssert, int size) {
+      return enumAssert.hasSizeLessThanOrEqualTo(size);
+    }
+  }
+
+  static final class EnumerableAssertHasSizeGreaterThan<E> {
+    @BeforeTemplate
+    AbstractIterableAssert<?, ?, E, ?> before(
+        AbstractIterableAssert<?, ?, E, ?> enumAssert, int size) {
+      return enumAssert.size().isGreaterThan(size).returnToIterable();
+    }
+
+    // XXX: If this template matches, then the expression's return type changes incompatibly.
+    // Consider moving this template to a separate block (statement) rule.
+    @BeforeTemplate
+    AbstractIterableSizeAssert<?, ?, E, ?> before2(
+        AbstractIterableAssert<?, ?, E, ?> enumAssert, int size) {
+      return enumAssert.size().isGreaterThan(size);
+    }
+
+    @AfterTemplate
+    EnumerableAssert<?, E> after(EnumerableAssert<?, E> enumAssert, int size) {
+      return enumAssert.hasSizeGreaterThan(size);
+    }
+  }
+
+  static final class EnumerableAssertHasSizeGreaterThanOrEqualTo<E> {
+    @BeforeTemplate
+    AbstractIterableAssert<?, ?, E, ?> before(
+        AbstractIterableAssert<?, ?, E, ?> enumAssert, int size) {
+      return enumAssert.size().isGreaterThanOrEqualTo(size).returnToIterable();
+    }
+
+    // XXX: If this template matches, then the expression's return type changes incompatibly.
+    // Consider moving this template to a separate block (statement) rule.
+    @BeforeTemplate
+    AbstractIterableSizeAssert<?, ?, E, ?> before2(
+        AbstractIterableAssert<?, ?, E, ?> enumAssert, int size) {
+      return enumAssert.size().isGreaterThanOrEqualTo(size);
+    }
+
+    @AfterTemplate
+    EnumerableAssert<?, E> after(EnumerableAssert<?, E> enumAssert, int size) {
+      return enumAssert.hasSizeGreaterThanOrEqualTo(size);
+    }
+  }
+
+  static final class EnumerableAssertHasSizeBetween<E> {
+    @BeforeTemplate
+    AbstractIterableAssert<?, ?, E, ?> before(
+        AbstractIterableAssert<?, ?, E, ?> enumAssert, int lower, int upper) {
+      return enumAssert.size().isBetween(lower, upper).returnToIterable();
+    }
+
+    // XXX: If this template matches, then the expression's return type changes incompatibly.
+    // Consider moving this template to a separate block (statement) rule.
+    @BeforeTemplate
+    AbstractIterableSizeAssert<?, ?, E, ?> before2(
+        AbstractIterableAssert<?, ?, E, ?> enumAssert, int lower, int upper) {
+      return enumAssert.size().isBetween(lower, upper);
+    }
+
+    @AfterTemplate
+    EnumerableAssert<?, E> after(EnumerableAssert<?, E> enumAssert, int lower, int upper) {
+      return enumAssert.hasSizeBetween(lower, upper);
+    }
+  }
+
+  static final class EnumerableAssertHasSameSizeAs<S, E> {
+    @BeforeTemplate
+    EnumerableAssert<?, S> before(EnumerableAssert<?, S> enumAssert, Iterable<E> iterable) {
       return enumAssert.hasSize(Iterables.size(iterable));
     }
 
     @BeforeTemplate
-    EnumerableAssert<?, S> before(EnumerableAssert<?, S> enumAssert, Collection<T> iterable) {
+    EnumerableAssert<?, S> before(EnumerableAssert<?, S> enumAssert, Collection<E> iterable) {
       return enumAssert.hasSize(iterable.size());
     }
 
     @BeforeTemplate
-    EnumerableAssert<?, S> before(EnumerableAssert<?, S> enumAssert, T[] iterable) {
+    EnumerableAssert<?, S> before(EnumerableAssert<?, S> enumAssert, E[] iterable) {
       return enumAssert.hasSize(iterable.length);
     }
 
     @AfterTemplate
-    EnumerableAssert<?, S> after(EnumerableAssert<?, S> enumAssert, Iterable<T> iterable) {
+    EnumerableAssert<?, S> after(EnumerableAssert<?, S> enumAssert, Iterable<E> iterable) {
       return enumAssert.hasSameSizeAs(iterable);
     }
   }

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

@@ -0,0 +1,90 @@
+package tech.picnic.errorprone.refasterrules;
+
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
+import static org.assertj.core.api.Assertions.assertThat;
+
+import com.google.common.collect.Iterables;
+import com.google.errorprone.refaster.annotation.AfterTemplate;
+import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import com.google.errorprone.refaster.annotation.UseImportPolicy;
+import java.util.Collection;
+import org.assertj.core.api.AbstractAssert;
+import org.assertj.core.api.AbstractIntegerAssert;
+import org.assertj.core.api.IterableAssert;
+import org.assertj.core.api.ObjectAssert;
+import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
+
+@OnlineDocumentation
+final class AssertJIterableRules {
+  private AssertJIterableRules() {}
+
+  static final class AssertThatIterableIsEmpty<E> {
+    @BeforeTemplate
+    void before(Iterable<E> iterable) {
+      assertThat(iterable.iterator()).isExhausted();
+    }
+
+    @BeforeTemplate
+    void before(Collection<E> iterable) {
+      assertThat(iterable.isEmpty()).isTrue();
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(Collection<E> iterable) {
+      assertThat(iterable).isEmpty();
+    }
+  }
+
+  static final class AssertThatIterableIsNotEmpty<E> {
+    @BeforeTemplate
+    AbstractAssert<?, ?> before(Iterable<E> iterable) {
+      return assertThat(iterable.iterator()).hasNext();
+    }
+
+    @BeforeTemplate
+    AbstractAssert<?, ?> before(Collection<E> iterable) {
+      return assertThat(iterable.isEmpty()).isFalse();
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    IterableAssert<E> after(Iterable<E> iterable) {
+      return assertThat(iterable).isNotEmpty();
+    }
+  }
+
+  static final class AssertThatIterableSize<E> {
+    @BeforeTemplate
+    AbstractIntegerAssert<?> before(Iterable<E> iterable) {
+      return assertThat(Iterables.size(iterable));
+    }
+
+    @BeforeTemplate
+    AbstractIntegerAssert<?> before(Collection<E> iterable) {
+      return assertThat(iterable.size());
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractIntegerAssert<?> after(Iterable<E> iterable) {
+      return assertThat(iterable).size();
+    }
+  }
+
+  // XXX: In practice this rule isn't very useful, as it only matches invocations of
+  // `assertThat(E)`. In most cases a more specific overload of `assertThat` is invoked, in which
+  // case this rule won't match. Look into a more robust approach.
+  static final class AssertThatIterableHasOneElementEqualTo<S, E extends S> {
+    @BeforeTemplate
+    ObjectAssert<S> before(Iterable<S> iterable, E element) {
+      return assertThat(Iterables.getOnlyElement(iterable)).isEqualTo(element);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    IterableAssert<S> after(Iterable<S> iterable, E element) {
+      return assertThat(iterable).containsExactly(element);
+    }
+  }
+}

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

@@ -0,0 +1,43 @@
+package tech.picnic.errorprone.refasterrules;
+
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
+import static org.assertj.core.api.Assertions.assertThat;
+
+import com.google.errorprone.refaster.annotation.AfterTemplate;
+import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import com.google.errorprone.refaster.annotation.UseImportPolicy;
+import java.util.Iterator;
+import org.assertj.core.api.AbstractBooleanAssert;
+import org.assertj.core.api.IteratorAssert;
+import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
+
+@OnlineDocumentation
+final class AssertJIteratorRules {
+  private AssertJIteratorRules() {}
+
+  static final class AssertThatHasNext<T> {
+    @BeforeTemplate
+    AbstractBooleanAssert<?> before(Iterator<T> iterator) {
+      return assertThat(iterator.hasNext()).isTrue();
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    IteratorAssert<T> after(Iterator<T> iterator) {
+      return assertThat(iterator).hasNext();
+    }
+  }
+
+  static final class AssertThatIsExhausted<T> {
+    @BeforeTemplate
+    AbstractBooleanAssert<?> before(Iterator<T> iterator) {
+      return assertThat(iterator.hasNext()).isFalse();
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    IteratorAssert<T> after(Iterator<T> iterator) {
+      return assertThat(iterator).isExhausted();
+    }
+  }
+}

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

@@ -11,7 +11,6 @@ import com.google.errorprone.refaster.annotation.Matches;
 import com.google.errorprone.refaster.annotation.UseImportPolicy;
 import java.util.Collection;
 import java.util.Map;
-import java.util.Set;
 import org.assertj.core.api.AbstractAssert;
 import org.assertj.core.api.AbstractBooleanAssert;
 import org.assertj.core.api.AbstractCollectionAssert;
@@ -182,13 +181,13 @@ final class AssertJMapRules {
   static final class AssertThatMapContainsOnlyKeys<K, V> {
     @BeforeTemplate
     AbstractCollectionAssert<?, Collection<? extends K>, K, ?> before(
-        Map<K, V> map, Set<? extends K> keys) {
+        Map<K, V> map, Iterable<? extends K> keys) {
       return assertThat(map.keySet()).hasSameElementsAs(keys);
     }
 
     @AfterTemplate
     @UseImportPolicy(STATIC_IMPORT_ALWAYS)
-    MapAssert<K, V> after(Map<K, V> map, Set<? extends K> keys) {
+    MapAssert<K, V> after(Map<K, V> map, Iterable<? extends K> keys) {
       return assertThat(map).containsOnlyKeys(keys);
     }
   }

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

@@ -12,6 +12,7 @@ import java.nio.charset.Charset;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import org.assertj.core.api.AbstractAssert;
+import org.assertj.core.api.AbstractBooleanAssert;
 import org.assertj.core.api.AbstractStringAssert;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 
@@ -31,19 +32,6 @@ final class AssertJStringRules {
     }
   }
 
-  static final class AssertThatStringIsEmpty {
-    @BeforeTemplate
-    void before(String string) {
-      assertThat(string.isEmpty()).isTrue();
-    }
-
-    @AfterTemplate
-    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
-    void after(String string) {
-      assertThat(string).isEmpty();
-    }
-  }
-
   static final class AbstractStringAssertStringIsNotEmpty {
     @BeforeTemplate
     AbstractStringAssert<?> before(AbstractStringAssert<?> stringAssert) {
@@ -56,16 +44,29 @@ final class AssertJStringRules {
     }
   }
 
-  static final class AssertThatStringIsNotEmpty {
+  static final class AssertThatStringContains {
     @BeforeTemplate
-    AbstractAssert<?, ?> before(String string) {
-      return assertThat(string.isEmpty()).isFalse();
+    AbstractBooleanAssert<?> before(String string, CharSequence substring) {
+      return assertThat(string.contains(substring)).isTrue();
     }
 
     @AfterTemplate
     @UseImportPolicy(STATIC_IMPORT_ALWAYS)
-    AbstractAssert<?, ?> after(String string) {
-      return assertThat(string).isNotEmpty();
+    AbstractStringAssert<?> after(String string, CharSequence substring) {
+      return assertThat(string).contains(substring);
+    }
+  }
+
+  static final class AssertThatStringDoesNotContain {
+    @BeforeTemplate
+    AbstractBooleanAssert<?> before(String string, CharSequence substring) {
+      return assertThat(string.contains(substring)).isFalse();
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractStringAssert<?> after(String string, CharSequence substring) {
+      return assertThat(string).doesNotContain(substring);
     }
   }
 

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

@@ -7,7 +7,10 @@ import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException
 import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
 import static org.assertj.core.api.Assertions.assertThatNullPointerException;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.assertj.core.api.InstanceOfAssertFactories.throwable;
+import static org.assertj.core.api.InstanceOfAssertFactories.type;
 
+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;
@@ -16,6 +19,7 @@ import java.io.IOException;
 import org.assertj.core.api.AbstractObjectAssert;
 import org.assertj.core.api.AbstractThrowableAssert;
 import org.assertj.core.api.ThrowableAssert.ThrowingCallable;
+import org.assertj.core.api.ThrowableAssertAlternative;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 
 /**
@@ -31,6 +35,21 @@ import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 final class AssertJThrowingCallableRules {
   private AssertJThrowingCallableRules() {}
 
+  static final class AssertThatThrownByIsInstanceOf<T extends Throwable> {
+    @BeforeTemplate
+    void before(ThrowingCallable throwingCallable, Class<T> exceptionType) {
+      Refaster.anyOf(
+          assertThatThrownBy(throwingCallable).asInstanceOf(throwable(exceptionType)),
+          assertThatThrownBy(throwingCallable).asInstanceOf(type(exceptionType)));
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(ThrowingCallable throwingCallable, Class<T> exceptionType) {
+      assertThatThrownBy(throwingCallable).isInstanceOf(exceptionType);
+    }
+  }
+
   static final class AssertThatThrownByIllegalArgumentException {
     @BeforeTemplate
     AbstractObjectAssert<?, ?> before(ThrowingCallable throwingCallable) {
@@ -61,6 +80,27 @@ final class AssertJThrowingCallableRules {
     }
   }
 
+  static final class AssertThatThrownByIllegalArgumentExceptionRootCauseHasMessage {
+    @BeforeTemplate
+    @SuppressWarnings(
+        "AssertThatThrownByIllegalArgumentException" /* This is a more specific template. */)
+    AbstractObjectAssert<?, ?> before(ThrowingCallable throwingCallable, String message) {
+      return assertThatIllegalArgumentException()
+          .isThrownBy(throwingCallable)
+          .havingRootCause()
+          .withMessage(message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(ThrowingCallable throwingCallable, String message) {
+      return assertThatThrownBy(throwingCallable)
+          .isInstanceOf(IllegalArgumentException.class)
+          .rootCause()
+          .hasMessage(message);
+    }
+  }
+
   static final class AssertThatThrownByIllegalArgumentExceptionHasMessageParameters {
     @BeforeTemplate
     @SuppressWarnings(
@@ -171,6 +211,27 @@ final class AssertJThrowingCallableRules {
     }
   }
 
+  static final class AssertThatThrownByIllegalStateExceptionRootCauseHasMessage {
+    @BeforeTemplate
+    @SuppressWarnings(
+        "AssertThatThrownByIllegalStateException" /* This is a more specific template. */)
+    AbstractObjectAssert<?, ?> before(ThrowingCallable throwingCallable, String message) {
+      return assertThatIllegalStateException()
+          .isThrownBy(throwingCallable)
+          .havingRootCause()
+          .withMessage(message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(ThrowingCallable throwingCallable, String message) {
+      return assertThatThrownBy(throwingCallable)
+          .isInstanceOf(IllegalStateException.class)
+          .rootCause()
+          .hasMessage(message);
+    }
+  }
+
   static final class AssertThatThrownByIllegalStateExceptionHasMessageParameters {
     @BeforeTemplate
     @SuppressWarnings(
@@ -279,6 +340,27 @@ final class AssertJThrowingCallableRules {
     }
   }
 
+  static final class AssertThatThrownByNullPointerExceptionRootCauseHasMessage {
+    @BeforeTemplate
+    @SuppressWarnings(
+        "AssertThatThrownByNullPointerException" /* This is a more specific template. */)
+    AbstractObjectAssert<?, ?> before(ThrowingCallable throwingCallable, String message) {
+      return assertThatNullPointerException()
+          .isThrownBy(throwingCallable)
+          .havingRootCause()
+          .withMessage(message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(ThrowingCallable throwingCallable, String message) {
+      return assertThatThrownBy(throwingCallable)
+          .isInstanceOf(NullPointerException.class)
+          .rootCause()
+          .hasMessage(message);
+    }
+  }
+
   static final class AssertThatThrownByNullPointerExceptionHasMessageParameters {
     @BeforeTemplate
     @SuppressWarnings(
@@ -386,6 +468,26 @@ final class AssertJThrowingCallableRules {
     }
   }
 
+  static final class AssertThatThrownByIOExceptionRootCauseHasMessage {
+    @BeforeTemplate
+    @SuppressWarnings("AssertThatThrownByIOException" /* This is a more specific template. */)
+    AbstractObjectAssert<?, ?> before(ThrowingCallable throwingCallable, String message) {
+      return assertThatIOException()
+          .isThrownBy(throwingCallable)
+          .havingRootCause()
+          .withMessage(message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(ThrowingCallable throwingCallable, String message) {
+      return assertThatThrownBy(throwingCallable)
+          .isInstanceOf(IOException.class)
+          .rootCause()
+          .hasMessage(message);
+    }
+  }
+
   static final class AssertThatThrownByIOExceptionHasMessageParameters {
     @BeforeTemplate
     @SuppressWarnings("AssertThatThrownByIOException" /* This is a more specific template. */)
@@ -452,27 +554,27 @@ final class AssertJThrowingCallableRules {
     }
   }
 
-  static final class AssertThatThrownBy {
+  static final class AssertThatThrownByAsInstanceOfThrowable<T extends Throwable> {
     @BeforeTemplate
-    AbstractObjectAssert<?, ?> before(
-        Class<? extends Throwable> exceptionType, ThrowingCallable throwingCallable) {
+    ThrowableAssertAlternative<T> before(
+        ThrowingCallable throwingCallable, Class<T> exceptionType) {
       return assertThatExceptionOfType(exceptionType).isThrownBy(throwingCallable);
     }
 
     @AfterTemplate
     @UseImportPolicy(STATIC_IMPORT_ALWAYS)
-    AbstractObjectAssert<?, ?> after(
-        Class<? extends Throwable> exceptionType, ThrowingCallable throwingCallable) {
-      return assertThatThrownBy(throwingCallable).isInstanceOf(exceptionType);
+    AbstractThrowableAssert<?, T> after(ThrowingCallable throwingCallable, Class<T> exceptionType) {
+      return assertThatThrownBy(throwingCallable).asInstanceOf(throwable(exceptionType));
     }
   }
 
   static final class AssertThatThrownByHasMessage {
     @BeforeTemplate
-    @SuppressWarnings("AssertThatThrownBy" /* This is a more specific template. */)
+    @SuppressWarnings(
+        "AssertThatThrownByAsInstanceOfThrowable" /* This is a more specific template. */)
     AbstractObjectAssert<?, ?> before(
-        Class<? extends Throwable> exceptionType,
         ThrowingCallable throwingCallable,
+        Class<? extends Throwable> exceptionType,
         String message) {
       return assertThatExceptionOfType(exceptionType)
           .isThrownBy(throwingCallable)
@@ -482,19 +584,47 @@ final class AssertJThrowingCallableRules {
     @AfterTemplate
     @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     AbstractObjectAssert<?, ?> after(
-        Class<? extends Throwable> exceptionType,
         ThrowingCallable throwingCallable,
+        Class<? extends Throwable> exceptionType,
         String message) {
       return assertThatThrownBy(throwingCallable).isInstanceOf(exceptionType).hasMessage(message);
     }
   }
 
+  static final class AssertThatThrownByRootCauseHasMessage {
+    @BeforeTemplate
+    @SuppressWarnings(
+        "AssertThatThrownByAsInstanceOfThrowable" /* This is a more specific template. */)
+    AbstractObjectAssert<?, ?> before(
+        ThrowingCallable throwingCallable,
+        Class<? extends Throwable> exceptionType,
+        String message) {
+      return assertThatExceptionOfType(exceptionType)
+          .isThrownBy(throwingCallable)
+          .havingRootCause()
+          .withMessage(message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    AbstractObjectAssert<?, ?> after(
+        ThrowingCallable throwingCallable,
+        Class<? extends Throwable> exceptionType,
+        String message) {
+      return assertThatThrownBy(throwingCallable)
+          .isInstanceOf(exceptionType)
+          .rootCause()
+          .hasMessage(message);
+    }
+  }
+
   static final class AssertThatThrownByHasMessageParameters {
     @BeforeTemplate
-    @SuppressWarnings("AssertThatThrownBy" /* This is a more specific template. */)
+    @SuppressWarnings(
+        "AssertThatThrownByAsInstanceOfThrowable" /* This is a more specific template. */)
     AbstractObjectAssert<?, ?> before(
-        Class<? extends Throwable> exceptionType,
         ThrowingCallable throwingCallable,
+        Class<? extends Throwable> exceptionType,
         String message,
         @Repeated Object parameters) {
       return assertThatExceptionOfType(exceptionType)
@@ -505,8 +635,8 @@ final class AssertJThrowingCallableRules {
     @AfterTemplate
     @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     AbstractObjectAssert<?, ?> after(
-        Class<? extends Throwable> exceptionType,
         ThrowingCallable throwingCallable,
+        Class<? extends Throwable> exceptionType,
         String message,
         @Repeated Object parameters) {
       return assertThatThrownBy(throwingCallable)
@@ -517,10 +647,11 @@ final class AssertJThrowingCallableRules {
 
   static final class AssertThatThrownByHasMessageStartingWith {
     @BeforeTemplate
-    @SuppressWarnings("AssertThatThrownBy" /* This is a more specific template. */)
+    @SuppressWarnings(
+        "AssertThatThrownByAsInstanceOfThrowable" /* This is a more specific template. */)
     AbstractObjectAssert<?, ?> before(
-        Class<? extends Throwable> exceptionType,
         ThrowingCallable throwingCallable,
+        Class<? extends Throwable> exceptionType,
         String message) {
       return assertThatExceptionOfType(exceptionType)
           .isThrownBy(throwingCallable)
@@ -530,8 +661,8 @@ final class AssertJThrowingCallableRules {
     @AfterTemplate
     @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     AbstractObjectAssert<?, ?> after(
-        Class<? extends Throwable> exceptionType,
         ThrowingCallable throwingCallable,
+        Class<? extends Throwable> exceptionType,
         String message) {
       return assertThatThrownBy(throwingCallable)
           .isInstanceOf(exceptionType)
@@ -541,10 +672,11 @@ final class AssertJThrowingCallableRules {
 
   static final class AssertThatThrownByHasMessageContaining {
     @BeforeTemplate
-    @SuppressWarnings("AssertThatThrownBy" /* This is a more specific template. */)
+    @SuppressWarnings(
+        "AssertThatThrownByAsInstanceOfThrowable" /* This is a more specific template. */)
     AbstractObjectAssert<?, ?> before(
-        Class<? extends Throwable> exceptionType,
         ThrowingCallable throwingCallable,
+        Class<? extends Throwable> exceptionType,
         String message) {
       return assertThatExceptionOfType(exceptionType)
           .isThrownBy(throwingCallable)
@@ -554,8 +686,8 @@ final class AssertJThrowingCallableRules {
     @AfterTemplate
     @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     AbstractObjectAssert<?, ?> after(
-        Class<? extends Throwable> exceptionType,
         ThrowingCallable throwingCallable,
+        Class<? extends Throwable> exceptionType,
         String message) {
       return assertThatThrownBy(throwingCallable)
           .isInstanceOf(exceptionType)
@@ -565,10 +697,11 @@ final class AssertJThrowingCallableRules {
 
   static final class AssertThatThrownByHasMessageNotContaining {
     @BeforeTemplate
-    @SuppressWarnings("AssertThatThrownBy" /* This is a more specific template. */)
+    @SuppressWarnings(
+        "AssertThatThrownByAsInstanceOfThrowable" /* This is a more specific template. */)
     AbstractObjectAssert<?, ?> before(
-        Class<? extends Throwable> exceptionType,
         ThrowingCallable throwingCallable,
+        Class<? extends Throwable> exceptionType,
         String message) {
       return assertThatExceptionOfType(exceptionType)
           .isThrownBy(throwingCallable)
@@ -578,8 +711,8 @@ final class AssertJThrowingCallableRules {
     @AfterTemplate
     @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     AbstractObjectAssert<?, ?> after(
-        Class<? extends Throwable> exceptionType,
         ThrowingCallable throwingCallable,
+        Class<? extends Throwable> exceptionType,
         String message) {
       return assertThatThrownBy(throwingCallable)
           .isInstanceOf(exceptionType)

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
@@ -145,18 +121,18 @@ final class AssortedRules {
    */
   static final class DisjointSets<T> {
     @BeforeTemplate
-    boolean before(Set<T> set1, Set<T> set2) {
-      return Sets.intersection(set1, set2).isEmpty();
+    boolean before(Set<T> collection1, Set<T> collection2) {
+      return Sets.intersection(collection1, collection2).isEmpty();
     }
 
     @BeforeTemplate
-    boolean before2(Set<T> set1, Set<T> set2) {
-      return set1.stream().noneMatch(set2::contains);
+    boolean before2(Collection<T> collection1, Collection<T> collection2) {
+      return collection1.stream().noneMatch(collection2::contains);
     }
 
     @AfterTemplate
-    boolean after(Set<T> set1, Set<T> set2) {
-      return disjoint(set1, set2);
+    boolean after(Collection<T> collection1, Collection<T> collection2) {
+      return disjoint(collection1, collection2);
     }
   }