[maven-release-plugin] prepare release v0.19.1

See:
- https://checkstyle.sourceforge.io/releasenotes.html
- https://github.com/checkstyle/checkstyle/releases/tag/checkstyle-10.20.0
- https://github.com/checkstyle/checkstyle/compare/checkstyle-10.19.0...checkstyle-10.20.0

.github/ISSUE_TEMPLATE/bug_report.md

@@ -42,9 +42,9 @@ Please replace this sentence with log output, if applicable.
 <!-- Please complete the following information: -->
 
 - Operating system (e.g. MacOS Monterey).
-- Java version (i.e. `java --version`, e.g. `17.0.8`).
-- 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

@@ -10,36 +10,43 @@ jobs:
     strategy:
       matrix:
         os: [ ubuntu-22.04 ]
-        jdk: [ 11.0.20, 17.0.8, 21.0.0 ]
+        jdk: [ 17.0.13, 21.0.5, 23.0.1 ]
         distribution: [ temurin ]
         experimental: [ false ]
         include:
-          - os: macos-12
-            jdk: 17.0.8
+          - os: macos-14
+            jdk: 17.0.13
             distribution: temurin
             experimental: false
           - os: windows-2022
-            jdk: 17.0.8
+            jdk: 17.0.13
             distribution: temurin
             experimental: false
     runs-on: ${{ matrix.os }}
     continue-on-error: ${{ matrix.experimental }}
     steps:
+      - name: Install Harden-Runner
+        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
+        with:
+          disable-sudo: true
+          egress-policy: block
+          allowed-endpoints: >
+            api.adoptium.net:443
+            github.com:443
+            jitpack.io: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@489441643219d2b93ee2a127b2402eb640a1b947 # v1.13.0
         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

.github/workflows/codeql.yml

@@ -21,24 +21,32 @@ jobs:
       security-events: write
     runs-on: ubuntu-22.04
     steps:
-      - name: Check out code
-        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+      - name: Install Harden-Runner
+        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
         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@489441643219d2b93ee2a127b2402eb640a1b947 # v1.13.0
         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@c7f9125735019aa87cfc361530512d50ea439c71 # v3.25.1
         with:
           languages: ${{ matrix.language }}
       - name: Perform minimal build
         if: matrix.language == 'java'
         run: mvn -T1C clean package -DskipTests -Dverification.skip
       - name: Perform CodeQL analysis
-        uses: github/codeql-action/analyze@407ffafae6a767df3e0230c3df91b6443ae8df75 # v2.22.8
+        uses: github/codeql-action/analyze@c7f9125735019aa87cfc361530512d50ea439c71 # v3.25.1
         with:
           category: /language:${{ matrix.language }}

.github/workflows/deploy-website.yml

@@ -11,16 +11,43 @@ jobs:
   build:
     runs-on: ubuntu-22.04
     steps:
+      - name: Install Harden-Runner
+        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
+        with:
+          disable-sudo: true
+          egress-policy: block
+          allowed-endpoints: >
+            api.adoptium.net:443
+            api.github.com:443
+            bestpractices.coreinfrastructure.org:443
+            blog.picnic.nl: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
-        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+        uses: actions/checkout@a5ac7e51b41094c92402da3b24376905380afc29 # v4.1.6
         with:
           persist-credentials: false
-      - uses: ruby/setup-ruby@8575951200e472d5f2d95c625da0c7bec8217c42 # v1.161.0
+      - uses: ruby/setup-ruby@6bd3d993c602f6b675728ebaecb2b569ff86e99b # v1.174.0
         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: Generate documentation
         run: ./generate-docs.sh
       - name: Build website with Jekyll
@@ -32,7 +59,7 @@ jobs:
         # "Refaster rules" terminology on our website and in the code.
         run: bundle exec htmlproofer --disable_external true --check-external-hash false ./_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:
@@ -46,6 +73,13 @@ jobs:
       name: github-pages
       url: ${{ steps.deployment.outputs.page_url }}
     steps:
+      - name: Install Harden-Runner
+        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
+        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

@@ -20,17 +20,31 @@ jobs:
       id-token: write
     runs-on: ubuntu-22.04
     steps:
+      - name: Install Harden-Runner
+        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
+        with:
+          disable-sudo: true
+          egress-policy: block
+          allowed-endpoints: >
+            api.github.com:443
+            api.osv.dev:443
+            api.scorecard.dev:443
+            api.securityscorecards.dev:443
+            github.com:443
+            oss-fuzz-build-logs.storage.googleapis.com:443
+            *.sigstore.dev:443
+            www.bestpractices.dev:443
       - name: Check out code
-        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+        uses: actions/checkout@a5ac7e51b41094c92402da3b24376905380afc29 # v4.1.6
         with:
           persist-credentials: false
       - name: Run OpenSSF Scorecard analysis
-        uses: ossf/scorecard-action@0864cf19026789058feabb7e87baa5f140aac736 # v2.3.1
+        uses: ossf/scorecard-action@dc50aa9510b46c811795eb24b2f1ba02a914e534 # v2.3.3
         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@c7f9125735019aa87cfc361530512d50ea439c71 # v3.25.1
         with:
           sarif_file: results.sarif

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

@@ -11,17 +11,23 @@ jobs:
   analyze-pr:
     runs-on: ubuntu-22.04
     steps:
-      - name: Check out code
-        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+      - name: Install Harden-Runner
+        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
         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@489441643219d2b93ee2a127b2402eb640a1b947 # v1.13.0
         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@65462800fd760344b1a7b4382951275a0abb4808 # v4.3.3
         with:
           name: pitest-reports
           path: ./target/pit-reports-ci

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

@@ -19,18 +19,25 @@ jobs:
       pull-requests: write
     runs-on: ubuntu-22.04
     steps:
-      - name: Check out code
-        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+      - name: Install Harden-Runner
+        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
         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@489441643219d2b93ee2a127b2402eb640a1b947 # v1.13.0
         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

@@ -18,26 +18,36 @@ jobs:
       github.event.issue.pull_request && contains(github.event.comment.body, '/integration-test')
     runs-on: ubuntu-22.04
     steps:
-      - name: Check out code
-        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+      - name: Install Harden-Runner
+        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
         with:
-          persist-credentials: false
-          ref: refs/pull/${{ github.event.issue.number }}/head
-      - name: Set up JDK
-        uses: actions/setup-java@387ac29b308b003ca37ba93a6cab5eb57c8f5f93 # v4.0.0
+          disable-sudo: true
+          egress-policy: block
+          allowed-endpoints: >
+            api.adoptium.net:443
+            checkstyle.org:443
+            github.com:443
+            objects.githubusercontent.com:443
+            oss.sonatype.org:443
+            raw.githubusercontent.com:443
+            repo.maven.apache.org:443
+            repository.sonatype.org:443
+      - name: Check out code and set up JDK and Maven
+        uses: s4u/setup-maven-action@489441643219d2b93ee2a127b2402eb640a1b947 # v1.13.0
         with:
-          java-version: 17.0.8
-          distribution: temurin
-          cache: maven
+          checkout-ref: "refs/pull/${{ 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 "${{ runner.temp }}/artifacts"
+        run: xvfb-run ./integration-tests/checkstyle.sh "${{ runner.temp }}/artifacts"
       - name: Upload artifacts on failure
         if: ${{ failure() }}
-        uses: actions/upload-artifact@c7d193f32edcb7bfad88892161225aeda64e9392 # v4.0.0
+        uses: actions/upload-artifact@65462800fd760344b1a7b4382951275a0abb4808 # v4.3.3
         with:
-          name: integration-test-checkstyle-10.12.4
+          name: integration-test-checkstyle
           path: "${{ runner.temp }}/artifacts"
       - name: Remove installed project artifacts
         run: mvn build-helper:remove-project-artifact

.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
     steps:
-      - name: Check out code
-        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+      - name: Install Harden-Runner
+        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
         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@489441643219d2b93ee2a127b2402eb640a1b947 # v1.13.0
         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)">
+                <path d="M1151.08,1881.86C1134.93,1883.99 1114.77,1892.69 1101.6,1913.17C1088.42,1933.64 1082.71,1963.73 1088.42,2007.04C1094.04,2049.75 1107.59,2099.16 1124.51,2138.68C1132.97,2158.45 1142.15,2175.68 1152.59,2188.86C1163.04,2202.05 1176.31,2213.89 1194.48,2211.5C1212.65,2209.11 1222.39,2194.23 1229.07,2178.8C1235.75,2163.36 1240.15,2144.34 1243.21,2123.05C1249.32,2080.5 1249.63,2029.27 1244,1986.56C1238.3,1943.24 1225,1915.66 1206.98,1899.29C1188.95,1882.93 1167.22,1879.74 1151.08,1881.86ZM1155.55,1915.81C1164.27,1914.66 1174.03,1915.62 1183.96,1924.64C1193.89,1933.66 1205.01,1952.69 1210.06,1991.03C1215.18,2029.97 1214.89,2079.4 1209.32,2118.19C1206.53,2137.58 1202.32,2154.4 1197.65,2165.2C1194.14,2173.29 1190.82,2176.3 1189.96,2177.22C1188.89,2176.55 1184.91,2174.51 1179.43,2167.6C1172.12,2158.38 1163.7,2143.22 1155.99,2125.21C1140.57,2089.18 1127.49,2041.51 1122.36,2002.57C1117.32,1964.24 1123.13,1942.97 1130.39,1931.69C1137.65,1920.42 1146.82,1916.96 1155.55,1915.81Z" style="fill:rgb(26,26,26);fill-rule:nonzero;"/>
+            </g>
+            <g transform="matrix(1,0,0,1,0,9.81959)">
+                <path d="M1516.33,1963.1C1466.19,1897.75 1427.4,1906.77 1407.5,1922.05C1387.59,1937.32 1368.84,1972.45 1418.98,2037.8C1431.75,2054.44 1447.26,2071.84 1463.69,2088.19C1495.18,2119.52 1534.33,2139.39 1582.98,2126.14C1606.4,2119.76 1622.19,2110.46 1623.75,2098.64C1625.79,2083.16 1603,2065.78 1569.69,2050.47C1554.75,2019.83 1535.59,1988.2 1516.33,1963.1Z" 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 transform="matrix(1,0,0,1,0,9.81959)">
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+            <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 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>
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+            <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

@@ -12,7 +12,8 @@
       "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>
@@ -263,6 +265,7 @@ 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
@@ -299,7 +302,7 @@ channel; please see our [security policy][security] for details.
 [refaster]: https://errorprone.info/docs/refaster
 [refaster-rules-bigdecimal]: https://github.com/PicnicSupermarket/error-prone-support/blob/master/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/BigDecimalRules.java
 [refaster-rules]: https://github.com/PicnicSupermarket/error-prone-support/blob/master/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/
-[reproducible-builds-badge]: https://img.shields.io/badge/Reproducible_Builds-ok-success?labelColor=1e5b96
+[reproducible-builds-badge]: https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/jvm-repo-rebuild/reproducible-central/master/content/tech/picnic/error-prone-support/error-prone-support/badge.json
 [reproducible-builds-report]: https://github.com/jvm-repo-rebuild/reproducible-central/blob/master/content/tech/picnic/error-prone-support/error-prone-support/README.md
 [script-apply-error-prone-suggestions]: https://github.com/PicnicSupermarket/error-prone-support/blob/master/apply-error-prone-suggestions.sh
 [script-run-branch-mutation-tests]: https://github.com/PicnicSupermarket/error-prone-support/blob/master/run-branch-mutation-tests.sh

documentation-support/pom.xml

@@ -5,13 +5,14 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.14.1-SNAPSHOT</version>
+        <version>0.19.1</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>
@@ -32,6 +33,15 @@
             <artifactId>error_prone_test_helpers</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>${project.groupId}</groupId>
+            <artifactId>error-prone-utils</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>${project.groupId}</groupId>
+            <artifactId>refaster-test-support</artifactId>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-annotations</artifactId>
@@ -40,6 +50,14 @@
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-databind</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>
@@ -73,6 +91,8 @@
             <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>

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/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/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/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

@@ -5,13 +5,14 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.14.1-SNAPSHOT</version>
+        <version>0.19.1</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>
@@ -47,10 +48,19 @@
             `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 +70,11 @@
         <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>
@@ -77,15 +87,16 @@
             <artifactId>auto-value-annotations</artifactId>
             <scope>provided</scope>
         </dependency>
-        <dependency>
-            <groupId>com.google.googlejavaformat</groupId>
-            <artifactId>google-java-format</artifactId>
-        </dependency>
         <dependency>
             <groupId>com.google.guava</groupId>
             <artifactId>guava</artifactId>
             <scope>provided</scope>
         </dependency>
+        <dependency>
+            <groupId>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>
@@ -161,6 +177,8 @@
             <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 +199,31 @@
             <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 +259,11 @@
             <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 +279,9 @@
                     <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 +299,58 @@
                             </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 +1,72 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.CUSTOM;
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
+
+import com.google.auto.service.AutoService;
+import com.google.common.collect.Iterables;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.LambdaExpressionTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.util.ASTHelpers;
+import com.sun.source.tree.LambdaExpressionTree;
+import com.sun.source.tree.TypeCastTree;
+import com.sun.source.tree.VariableTree;
+import com.sun.tools.javac.code.Type;
+import tech.picnic.errorprone.utils.SourceCode;
+
+/**
+ * A {@link BugChecker} that flags lambda expressions that can be replaced with a method reference
+ * of the form {@code T.class::cast}.
+ */
+// XXX: Consider folding this logic into the `MethodReferenceUsage` check of the
+// `error-prone-experimental` module.
+// XXX: This check and its tests are structurally nearly identical to `IsInstanceLambdaUsage`.
+// Unless folded into `MethodReferenceUsage`, consider merging the two.
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "Prefer `Class::cast` method reference over equivalent lambda expression",
+    link = BUG_PATTERNS_BASE_URL + "ClassCastLambdaUsage",
+    linkType = CUSTOM,
+    severity = SUGGESTION,
+    tags = SIMPLIFICATION)
+public final class ClassCastLambdaUsage extends BugChecker implements LambdaExpressionTreeMatcher {
+  private static final long serialVersionUID = 1L;
+
+  /** Instantiates a new {@link ClassCastLambdaUsage} instance. */
+  public ClassCastLambdaUsage() {}
+
+  @Override
+  public Description matchLambdaExpression(LambdaExpressionTree tree, VisitorState state) {
+    if (tree.getParameters().size() != 1 || !(tree.getBody() instanceof TypeCastTree typeCast)) {
+      return Description.NO_MATCH;
+    }
+
+    Type type = ASTHelpers.getType(typeCast);
+    if (type == null || type.isParameterized() || type.isPrimitive()) {
+      /*
+       * The method reference syntax does not support casting to parameterized types. Additionally,
+       * `Class#cast` does not support the same range of type conversions between (boxed) primitive
+       * types as the cast operator.
+       */
+      // XXX: Depending on the declared type of the value being cast, in some cases we _can_ rewrite
+      // primitive casts. Add support for this.
+      return Description.NO_MATCH;
+    }
+
+    VariableTree param = Iterables.getOnlyElement(tree.getParameters());
+    if (!ASTHelpers.getSymbol(param).equals(ASTHelpers.getSymbol(typeCast.getExpression()))) {
+      return Description.NO_MATCH;
+    }
+
+    return describeMatch(
+        tree,
+        SuggestedFix.replace(
+            tree, SourceCode.treeToString(typeCast.getType(), state) + ".class::cast"));
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/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/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/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;
@@ -29,7 +41,7 @@ import com.sun.tools.javac.code.Type;
 import com.sun.tools.javac.code.Types;
 import java.util.Arrays;
 import java.util.List;
-import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+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 +51,7 @@ 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 +69,22 @@ 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(Matchers.class.getCanonicalName()).namedAnyOf("allOf", "anyOf"),
           staticMethod().onClass("reactor.adapter.rxjava.RxJava2Adapter"),
           staticMethod()
               .onClass("reactor.core.publisher.Flux")
@@ -114,8 +125,9 @@ 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:

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 +29,14 @@ 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.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 +67,14 @@ 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(),
+          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 +93,8 @@ 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 +105,10 @@ 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 +129,6 @@ public final class NonStaticImport extends BugChecker implements CompilationUnit
           "builder",
           "copyOf",
           "create",
-          "empty",
           "from",
           "getDefaultInstance",
           "INSTANCE",
@@ -127,10 +139,8 @@ 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 +169,9 @@ 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,
@@ -201,7 +210,7 @@ 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/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;
@@ -23,7 +23,7 @@ import com.sun.source.tree.MethodInvocationTree;
 import com.sun.source.tree.Tree.Kind;
 import java.util.List;
 import java.util.Optional;
-import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+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

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 =
+      "Slf4jLogDeclaration: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
@@ -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;
@@ -28,7 +28,7 @@ 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
@@ -49,7 +49,7 @@ 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);

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

@@ -10,7 +10,7 @@ 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;
@@ -34,7 +34,9 @@ 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,
@@ -45,11 +47,11 @@ public final class TimeZoneUsage extends BugChecker implements MethodInvocationT
       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",
@@ -59,14 +61,17 @@ public final class TimeZoneUsage extends BugChecker implements MethodInvocationT
                   "tickSeconds"),
           staticMethod()
               .onClassAny(
-                  LocalDate.class.getName(),
-                  LocalDateTime.class.getName(),
-                  LocalTime.class.getName(),
-                  OffsetDateTime.class.getName(),
-                  OffsetTime.class.getName(),
-                  ZonedDateTime.class.getName())
+                  LocalDate.class.getCanonicalName(),
+                  LocalDateTime.class.getCanonicalName(),
+                  LocalTime.class.getCanonicalName(),
+                  OffsetDateTime.class.getCanonicalName(),
+                  OffsetTime.class.getCanonicalName(),
+                  ZonedDateTime.class.getCanonicalName())
               .named("now"),
-          staticMethod().onClassAny(Instant.class.getName()).named("now").withNoParameters());
+          staticMethod()
+              .onClassAny(Instant.class.getCanonicalName())
+              .named("now")
+              .withNoParameters());
 
   /** Instantiates a new {@link TimeZoneUsage} instance. */
   public TimeZoneUsage() {}

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/refasterrules/AssertJRules.java

@@ -530,13 +530,13 @@ final class AssertJRules {
   static final class AssertThatStreamContainsAnyElementsOf<S, T extends S, U extends T> {
     @BeforeTemplate
     IterableAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends Iterable<T>> collector, Iterable<U> iterable) {
+        Stream<S> stream, Iterable<U> iterable, Collector<S, ?, ? extends Iterable<T>> collector) {
       return assertThat(stream.collect(collector)).containsAnyElementsOf(iterable);
     }
 
     @BeforeTemplate
     ListAssert<T> before2(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, Iterable<U> iterable) {
+        Stream<S> stream, Iterable<U> iterable, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).containsAnyElementsOf(iterable);
     }
 
@@ -551,13 +551,13 @@ final class AssertJRules {
   static final class AssertThatStreamContainsAnyOf<S, T extends S, U extends T> {
     @BeforeTemplate
     IterableAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends Iterable<T>> collector, U[] array) {
+        Stream<S> stream, U[] array, Collector<S, ?, ? extends Iterable<T>> collector) {
       return assertThat(stream.collect(collector)).containsAnyOf(array);
     }
 
     @BeforeTemplate
     ListAssert<T> before2(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, U[] array) {
+        Stream<S> stream, U[] array, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).containsAnyOf(array);
     }
 
@@ -573,14 +573,14 @@ final class AssertJRules {
     @BeforeTemplate
     @SuppressWarnings("AssertThatStreamContainsAnyOf" /* Varargs converted to array. */)
     IterableAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends Iterable<T>> collector, @Repeated U elements) {
+        Stream<S> stream, @Repeated U elements, Collector<S, ?, ? extends Iterable<T>> collector) {
       return assertThat(stream.collect(collector)).containsAnyOf(Refaster.asVarargs(elements));
     }
 
     @BeforeTemplate
     @SuppressWarnings("AssertThatStreamContainsAnyOf" /* Varargs converted to array. */)
     ListAssert<T> before2(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, @Repeated U elements) {
+        Stream<S> stream, @Repeated U elements, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).containsAnyOf(Refaster.asVarargs(elements));
     }
 
@@ -596,13 +596,13 @@ final class AssertJRules {
   static final class AssertThatStreamContainsAll<S, T extends S, U extends T> {
     @BeforeTemplate
     IterableAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends Iterable<T>> collector, Iterable<U> iterable) {
+        Stream<S> stream, Iterable<U> iterable, Collector<S, ?, ? extends Iterable<T>> collector) {
       return assertThat(stream.collect(collector)).containsAll(iterable);
     }
 
     @BeforeTemplate
     ListAssert<T> before2(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, Iterable<U> iterable) {
+        Stream<S> stream, Iterable<U> iterable, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).containsAll(iterable);
     }
 
@@ -617,13 +617,13 @@ final class AssertJRules {
   static final class AssertThatStreamContains<S, T extends S, U extends T> {
     @BeforeTemplate
     IterableAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends Iterable<T>> collector, U[] array) {
+        Stream<S> stream, U[] array, Collector<S, ?, ? extends Iterable<T>> collector) {
       return assertThat(stream.collect(collector)).contains(array);
     }
 
     @BeforeTemplate
     ListAssert<T> before2(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, U[] array) {
+        Stream<S> stream, U[] array, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).contains(array);
     }
 
@@ -639,14 +639,14 @@ final class AssertJRules {
     @BeforeTemplate
     @SuppressWarnings("AssertThatStreamContains" /* Varargs converted to array. */)
     IterableAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends Iterable<T>> collector, @Repeated U elements) {
+        Stream<S> stream, @Repeated U elements, Collector<S, ?, ? extends Iterable<T>> collector) {
       return assertThat(stream.collect(collector)).contains(Refaster.asVarargs(elements));
     }
 
     @BeforeTemplate
     @SuppressWarnings("AssertThatStreamContains" /* Varargs converted to array. */)
     ListAssert<T> before2(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, @Repeated U elements) {
+        Stream<S> stream, @Repeated U elements, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).contains(Refaster.asVarargs(elements));
     }
 
@@ -661,7 +661,7 @@ final class AssertJRules {
   static final class AssertThatStreamContainsExactlyElementsOf<S, T extends S, U extends T> {
     @BeforeTemplate
     ListAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, Iterable<U> iterable) {
+        Stream<S> stream, Iterable<U> iterable, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).containsExactlyElementsOf(iterable);
     }
 
@@ -676,7 +676,7 @@ final class AssertJRules {
   static final class AssertThatStreamContainsExactly<S, T extends S, U extends T> {
     @BeforeTemplate
     ListAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, U[] array) {
+        Stream<S> stream, U[] array, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).containsExactly(array);
     }
 
@@ -692,7 +692,7 @@ final class AssertJRules {
     @BeforeTemplate
     @SuppressWarnings("AssertThatStreamContainsExactly" /* Varargs converted to array. */)
     ListAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, @Repeated U elements) {
+        Stream<S> stream, @Repeated U elements, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).containsExactly(Refaster.asVarargs(elements));
     }
 
@@ -708,13 +708,13 @@ final class AssertJRules {
       S, T extends S, U extends T> {
     @BeforeTemplate
     ListAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, Iterable<U> iterable) {
+        Stream<S> stream, Iterable<U> iterable, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).containsExactlyInAnyOrderElementsOf(iterable);
     }
 
     @BeforeTemplate
     AbstractCollectionAssert<?, ?, T, ?> before2(
-        Stream<S> stream, Collector<S, ?, ? extends Multiset<T>> collector, Iterable<U> iterable) {
+        Stream<S> stream, Iterable<U> iterable, Collector<S, ?, ? extends Multiset<T>> collector) {
       return assertThat(stream.collect(collector)).containsExactlyInAnyOrderElementsOf(iterable);
     }
 
@@ -729,13 +729,13 @@ final class AssertJRules {
   static final class AssertThatStreamContainsExactlyInAnyOrder<S, T extends S, U extends T> {
     @BeforeTemplate
     ListAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, U[] array) {
+        Stream<S> stream, U[] array, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).containsExactlyInAnyOrder(array);
     }
 
     @BeforeTemplate
     AbstractCollectionAssert<?, ?, T, ?> before2(
-        Stream<S> stream, Collector<S, ?, ? extends Multiset<T>> collector, U[] array) {
+        Stream<S> stream, U[] array, Collector<S, ?, ? extends Multiset<T>> collector) {
       return assertThat(stream.collect(collector)).containsExactlyInAnyOrder(array);
     }
 
@@ -751,7 +751,7 @@ final class AssertJRules {
     @BeforeTemplate
     @SuppressWarnings("AssertThatStreamContainsExactlyInAnyOrder" /* Varargs converted to array. */)
     ListAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, @Repeated U elements) {
+        Stream<S> stream, @Repeated U elements, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector))
           .containsExactlyInAnyOrder(Refaster.asVarargs(elements));
     }
@@ -759,7 +759,7 @@ final class AssertJRules {
     @BeforeTemplate
     @SuppressWarnings("AssertThatStreamContainsExactlyInAnyOrder" /* Varargs converted to array. */)
     AbstractCollectionAssert<?, ?, T, ?> before2(
-        Stream<S> stream, Collector<S, ?, ? extends Multiset<T>> collector, @Repeated U elements) {
+        Stream<S> stream, @Repeated U elements, Collector<S, ?, ? extends Multiset<T>> collector) {
       return assertThat(stream.collect(collector))
           .containsExactlyInAnyOrder(Refaster.asVarargs(elements));
     }
@@ -776,13 +776,13 @@ final class AssertJRules {
   static final class AssertThatStreamContainsSequence<S, T extends S, U extends T> {
     @BeforeTemplate
     ListAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, Iterable<U> iterable) {
+        Stream<S> stream, Iterable<U> iterable, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).containsSequence(iterable);
     }
 
     @BeforeTemplate
     ListAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, U[] iterable) {
+        Stream<S> stream, U[] iterable, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).containsSequence(iterable);
     }
 
@@ -798,7 +798,7 @@ final class AssertJRules {
     @BeforeTemplate
     @SuppressWarnings("AssertThatStreamContainsSequence" /* Varargs converted to array. */)
     ListAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, @Repeated U elements) {
+        Stream<S> stream, @Repeated U elements, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).containsSequence(Refaster.asVarargs(elements));
     }
 
@@ -814,13 +814,13 @@ final class AssertJRules {
   static final class AssertThatStreamContainsSubsequence<S, T extends S, U extends T> {
     @BeforeTemplate
     ListAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, Iterable<U> iterable) {
+        Stream<S> stream, Iterable<U> iterable, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).containsSubsequence(iterable);
     }
 
     @BeforeTemplate
     ListAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, U[] iterable) {
+        Stream<S> stream, U[] iterable, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).containsSubsequence(iterable);
     }
 
@@ -836,7 +836,7 @@ final class AssertJRules {
     @BeforeTemplate
     @SuppressWarnings("AssertThatStreamContainsSubsequence" /* Varargs converted to array. */)
     ListAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, @Repeated U elements) {
+        Stream<S> stream, @Repeated U elements, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector))
           .containsSubsequence(Refaster.asVarargs(elements));
     }
@@ -853,13 +853,13 @@ final class AssertJRules {
   static final class AssertThatStreamDoesNotContainAnyElementsOf<S, T extends S, U extends T> {
     @BeforeTemplate
     IterableAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends Iterable<T>> collector, Iterable<U> iterable) {
+        Stream<S> stream, Iterable<U> iterable, Collector<S, ?, ? extends Iterable<T>> collector) {
       return assertThat(stream.collect(collector)).doesNotContainAnyElementsOf(iterable);
     }
 
     @BeforeTemplate
     ListAssert<T> before2(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, Iterable<U> iterable) {
+        Stream<S> stream, Iterable<U> iterable, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).doesNotContainAnyElementsOf(iterable);
     }
 
@@ -874,13 +874,13 @@ final class AssertJRules {
   static final class AssertThatStreamDoesNotContain<S, T extends S, U extends T> {
     @BeforeTemplate
     IterableAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends Iterable<T>> collector, U[] array) {
+        Stream<S> stream, U[] array, Collector<S, ?, ? extends Iterable<T>> collector) {
       return assertThat(stream.collect(collector)).doesNotContain(array);
     }
 
     @BeforeTemplate
     ListAssert<T> before2(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, U[] array) {
+        Stream<S> stream, U[] array, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).doesNotContain(array);
     }
 
@@ -896,14 +896,14 @@ final class AssertJRules {
     @BeforeTemplate
     @SuppressWarnings("AssertThatStreamDoesNotContain" /* Varargs converted to array. */)
     IterableAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends Iterable<T>> collector, @Repeated U elements) {
+        Stream<S> stream, @Repeated U elements, Collector<S, ?, ? extends Iterable<T>> collector) {
       return assertThat(stream.collect(collector)).doesNotContain(Refaster.asVarargs(elements));
     }
 
     @BeforeTemplate
     @SuppressWarnings("AssertThatStreamDoesNotContain" /* Varargs converted to array. */)
     ListAssert<T> before2(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, @Repeated U elements) {
+        Stream<S> stream, @Repeated U elements, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).doesNotContain(Refaster.asVarargs(elements));
     }
 
@@ -918,13 +918,13 @@ final class AssertJRules {
   static final class AssertThatStreamDoesNotContainSequence<S, T extends S, U extends T> {
     @BeforeTemplate
     ListAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, Iterable<U> iterable) {
+        Stream<S> stream, Iterable<U> iterable, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).doesNotContainSequence(iterable);
     }
 
     @BeforeTemplate
     ListAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, U[] iterable) {
+        Stream<S> stream, U[] iterable, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).doesNotContainSequence(iterable);
     }
 
@@ -940,7 +940,7 @@ final class AssertJRules {
     @BeforeTemplate
     @SuppressWarnings("AssertThatStreamDoesNotContainSequence" /* Varargs converted to array. */)
     ListAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, @Repeated U elements) {
+        Stream<S> stream, @Repeated U elements, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector))
           .doesNotContainSequence(Refaster.asVarargs(elements));
     }
@@ -957,13 +957,13 @@ final class AssertJRules {
   static final class AssertThatStreamHasSameElementsAs<S, T extends S, U extends T> {
     @BeforeTemplate
     IterableAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends Iterable<T>> collector, Iterable<U> iterable) {
+        Stream<S> stream, Iterable<U> iterable, Collector<S, ?, ? extends Iterable<T>> collector) {
       return assertThat(stream.collect(collector)).hasSameElementsAs(iterable);
     }
 
     @BeforeTemplate
     ListAssert<T> before2(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, Iterable<U> iterable) {
+        Stream<S> stream, Iterable<U> iterable, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).hasSameElementsAs(iterable);
     }
 
@@ -978,13 +978,13 @@ final class AssertJRules {
   static final class AssertThatStreamContainsOnly<S, T extends S, U extends T> {
     @BeforeTemplate
     IterableAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends Iterable<T>> collector, U[] array) {
+        Stream<S> stream, U[] array, Collector<S, ?, ? extends Iterable<T>> collector) {
       return assertThat(stream.collect(collector)).containsOnly(array);
     }
 
     @BeforeTemplate
     ListAssert<T> before2(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, U[] array) {
+        Stream<S> stream, U[] array, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).containsOnly(array);
     }
 
@@ -1000,14 +1000,14 @@ final class AssertJRules {
     @BeforeTemplate
     @SuppressWarnings("AssertThatStreamContainsOnly" /* Varargs converted to array. */)
     IterableAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends Iterable<T>> collector, @Repeated U elements) {
+        Stream<S> stream, @Repeated U elements, Collector<S, ?, ? extends Iterable<T>> collector) {
       return assertThat(stream.collect(collector)).containsOnly(Refaster.asVarargs(elements));
     }
 
     @BeforeTemplate
     @SuppressWarnings("AssertThatStreamContainsOnly" /* Varargs converted to array. */)
     ListAssert<T> before2(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, @Repeated U elements) {
+        Stream<S> stream, @Repeated U elements, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).containsOnly(Refaster.asVarargs(elements));
     }
 
@@ -1022,25 +1022,25 @@ final class AssertJRules {
   static final class AssertThatStreamIsSubsetOf<S, T extends S, U extends T> {
     @BeforeTemplate
     IterableAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends Iterable<T>> collector, Iterable<U> iterable) {
+        Stream<S> stream, Iterable<U> iterable, Collector<S, ?, ? extends Iterable<T>> collector) {
       return assertThat(stream.collect(collector)).isSubsetOf(iterable);
     }
 
     @BeforeTemplate
     IterableAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends Iterable<T>> collector, U[] iterable) {
+        Stream<S> stream, U[] iterable, Collector<S, ?, ? extends Iterable<T>> collector) {
       return assertThat(stream.collect(collector)).isSubsetOf(iterable);
     }
 
     @BeforeTemplate
     ListAssert<T> before2(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, Iterable<U> iterable) {
+        Stream<S> stream, Iterable<U> iterable, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).isSubsetOf(iterable);
     }
 
     @BeforeTemplate
     ListAssert<T> before2(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, U[] iterable) {
+        Stream<S> stream, U[] iterable, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).isSubsetOf(iterable);
     }
 
@@ -1056,14 +1056,14 @@ final class AssertJRules {
     @BeforeTemplate
     @SuppressWarnings("AssertThatStreamIsSubsetOf" /* Varargs converted to array. */)
     IterableAssert<T> before(
-        Stream<S> stream, Collector<S, ?, ? extends Iterable<T>> collector, @Repeated U elements) {
+        Stream<S> stream, @Repeated U elements, Collector<S, ?, ? extends Iterable<T>> collector) {
       return assertThat(stream.collect(collector)).isSubsetOf(Refaster.asVarargs(elements));
     }
 
     @BeforeTemplate
     @SuppressWarnings("AssertThatStreamIsSubsetOf" /* Varargs converted to array. */)
     ListAssert<T> before2(
-        Stream<S> stream, Collector<S, ?, ? extends List<T>> collector, @Repeated U elements) {
+        Stream<S> stream, @Repeated U elements, Collector<S, ?, ? extends List<T>> collector) {
       return assertThat(stream.collect(collector)).isSubsetOf(Refaster.asVarargs(elements));
     }
 

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

@@ -455,14 +455,14 @@ final class AssertJThrowingCallableRules {
   static final class AssertThatThrownBy {
     @BeforeTemplate
     AbstractObjectAssert<?, ?> before(
-        Class<? extends Throwable> exceptionType, ThrowingCallable throwingCallable) {
+        ThrowingCallable throwingCallable, Class<? extends Throwable> exceptionType) {
       return assertThatExceptionOfType(exceptionType).isThrownBy(throwingCallable);
     }
 
     @AfterTemplate
     @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     AbstractObjectAssert<?, ?> after(
-        Class<? extends Throwable> exceptionType, ThrowingCallable throwingCallable) {
+        ThrowingCallable throwingCallable, Class<? extends Throwable> exceptionType) {
       return assertThatThrownBy(throwingCallable).isInstanceOf(exceptionType);
     }
   }
@@ -471,8 +471,8 @@ final class AssertJThrowingCallableRules {
     @BeforeTemplate
     @SuppressWarnings("AssertThatThrownBy" /* 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)
@@ -482,8 +482,8 @@ 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).hasMessage(message);
     }
@@ -493,8 +493,8 @@ final class AssertJThrowingCallableRules {
     @BeforeTemplate
     @SuppressWarnings("AssertThatThrownBy" /* 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 +505,8 @@ 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)
@@ -519,8 +519,8 @@ final class AssertJThrowingCallableRules {
     @BeforeTemplate
     @SuppressWarnings("AssertThatThrownBy" /* 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 +530,8 @@ 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)
@@ -543,8 +543,8 @@ final class AssertJThrowingCallableRules {
     @BeforeTemplate
     @SuppressWarnings("AssertThatThrownBy" /* 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 +554,8 @@ 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)
@@ -567,8 +567,8 @@ final class AssertJThrowingCallableRules {
     @BeforeTemplate
     @SuppressWarnings("AssertThatThrownBy" /* 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 +578,8 @@ 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

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

@@ -9,6 +9,7 @@ import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import com.sun.tools.javac.util.Constants;
 import com.sun.tools.javac.util.Convert;
+import javax.lang.model.element.Name;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 
 /** Refaster rules related to {@link com.google.errorprone.bugpatterns.BugChecker} classes. */
@@ -67,4 +68,22 @@ final class BugCheckerRules {
       return Constants.format(value);
     }
   }
+
+  /** Prefer {@link Name#contentEquals(CharSequence)} over more verbose alternatives. */
+  static final class NameContentEquals {
+    @BeforeTemplate
+    boolean before(Name name, CharSequence string) {
+      return name.toString().equals(string.toString());
+    }
+
+    @BeforeTemplate
+    boolean before(Name name, String string) {
+      return name.toString().equals(string);
+    }
+
+    @AfterTemplate
+    boolean after(Name name, CharSequence string) {
+      return name.contentEquals(string);
+    }
+  }
 }

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

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

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

@@ -8,7 +8,9 @@ import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.AlsoNegation;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import com.google.errorprone.refaster.annotation.NotMatches;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.List;
@@ -21,6 +23,7 @@ import java.util.function.Consumer;
 import java.util.function.IntFunction;
 import java.util.stream.Stream;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
+import tech.picnic.errorprone.refaster.matchers.IsRefasterAsVarargs;
 
 /** Refaster rules related to expressions dealing with (arbitrary) collections. */
 // XXX: There are other Guava `Iterables` methods that should not be called if the input is known to
@@ -35,13 +38,21 @@ final class CollectionRules {
    */
   static final class CollectionIsEmpty<T> {
     @BeforeTemplate
-    @SuppressWarnings("java:S1155" /* This violation will be rewritten. */)
+    @SuppressWarnings({
+      "java:S1155" /* This violation will be rewritten. */,
+      "LexicographicalAnnotationAttributeListing" /* `key-*` entry must remain last. */,
+      "OptionalFirstCollectionElement" /* This is a more specific template. */,
+      "StreamFindAnyIsEmpty" /* This is a more specific template. */,
+      "key-to-resolve-AnnotationUseStyle-and-TrailingComment-check-conflict"
+    })
     boolean before(Collection<T> collection) {
       return Refaster.anyOf(
           collection.size() == 0,
           collection.size() <= 0,
           collection.size() < 1,
-          Iterables.isEmpty(collection));
+          Iterables.isEmpty(collection),
+          collection.stream().findAny().isEmpty(),
+          collection.stream().findFirst().isEmpty());
     }
 
     @BeforeTemplate
@@ -176,6 +187,24 @@ final class CollectionRules {
     }
   }
 
+  /** Don't unnecessarily call {@link Stream#distinct()} on an already-unique stream of elements. */
+  // XXX: This rule assumes that the `Set` relies on `Object#equals`, rather than a custom
+  // equivalence relation.
+  // XXX: Expressions that drop or reorder elements from the stream, such as `.filter`, `.skip` and
+  // `sorted`, can similarly be simplified. Covering all cases is better done using an Error Prone
+  // check.
+  static final class SetStream<T> {
+    @BeforeTemplate
+    Stream<?> before(Set<T> set) {
+      return set.stream().distinct();
+    }
+
+    @AfterTemplate
+    Stream<?> after(Set<T> set) {
+      return set.stream();
+    }
+  }
+
   /** Prefer {@link ArrayList#ArrayList(Collection)} over the Guava alternative. */
   @SuppressWarnings(
       "NonApiType" /* Matching against `List` would unnecessarily constrain the rule. */)
@@ -268,6 +297,23 @@ final class CollectionRules {
     }
   }
 
+  /** Prefer {@link Arrays#asList(Object[])} over more contrived alternatives. */
+  // XXX: Consider moving this rule to `ImmutableListRules` and having it suggest
+  // `ImmutableList#copyOf`. That would retain immutability, at the cost of no longer handling
+  // `null`s.
+  static final class ArraysAsList<T> {
+    // XXX: This expression produces an unmodifiable list, while the alternative doesn't.
+    @BeforeTemplate
+    List<T> before(@NotMatches(IsRefasterAsVarargs.class) T[] array) {
+      return Arrays.stream(array).toList();
+    }
+
+    @AfterTemplate
+    List<T> after(T[] array) {
+      return Arrays.asList(array);
+    }
+  }
+
   /** Prefer calling {@link Collection#toArray()} over more contrived alternatives. */
   static final class CollectionToArray<T> {
     @BeforeTemplate
@@ -319,25 +365,29 @@ final class CollectionRules {
     }
   }
 
-  /**
-   * Don't call {@link ImmutableCollection#asList()} if {@link ImmutableCollection#iterator()} is
-   * called on the result; call it directly.
-   */
-  static final class ImmutableCollectionIterator<T> {
+  /** Prefer {@link Collection#iterator()} over more contrived or less efficient alternatives. */
+  static final class CollectionIterator<T> {
+    @BeforeTemplate
+    Iterator<T> before(Collection<T> collection) {
+      return collection.stream().iterator();
+    }
+
     @BeforeTemplate
     Iterator<T> before(ImmutableCollection<T> collection) {
       return collection.asList().iterator();
     }
 
     @AfterTemplate
-    Iterator<T> after(ImmutableCollection<T> collection) {
+    Iterator<T> after(Collection<T> collection) {
       return collection.iterator();
     }
   }
 
   /**
    * Don't use the ternary operator to extract the first element of a possibly-empty {@link
-   * Collection} as an {@link Optional}.
+   * Collection} as an {@link Optional}, and (when applicable) prefer {@link Stream#findFirst()}
+   * over {@link Stream#findAny()} to communicate that the collection's first element (if any,
+   * according to iteration order) will be returned.
    */
   static final class OptionalFirstCollectionElement<T> {
     @BeforeTemplate

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

@@ -7,6 +7,8 @@ import static java.util.Comparator.comparingInt;
 import static java.util.Comparator.comparingLong;
 import static java.util.Comparator.naturalOrder;
 import static java.util.Comparator.reverseOrder;
+import static java.util.stream.Collectors.maxBy;
+import static java.util.stream.Collectors.minBy;
 
 import com.google.common.collect.Comparators;
 import com.google.common.collect.ImmutableList;
@@ -14,18 +16,25 @@ import com.google.common.collect.ImmutableSet;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
+import com.google.errorprone.refaster.annotation.AlsoNegation;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import com.google.errorprone.refaster.annotation.Matches;
+import com.google.errorprone.refaster.annotation.MayOptionallyUse;
+import com.google.errorprone.refaster.annotation.Placeholder;
 import com.google.errorprone.refaster.annotation.Repeated;
 import com.google.errorprone.refaster.annotation.UseImportPolicy;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.List;
+import java.util.Optional;
 import java.util.function.BinaryOperator;
 import java.util.function.Function;
 import java.util.function.ToDoubleFunction;
 import java.util.function.ToIntFunction;
 import java.util.function.ToLongFunction;
+import java.util.stream.Collector;
 import java.util.stream.Stream;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 import tech.picnic.errorprone.refaster.matchers.IsIdentityOperation;
@@ -88,6 +97,24 @@ final class ComparatorRules {
     }
   }
 
+  /** Don't explicitly compare enums by their ordinal. */
+  abstract static class ComparingEnum<E extends Enum<E>, T> {
+    @Placeholder(allowsIdentity = true)
+    abstract E toEnumFunction(@MayOptionallyUse T value);
+
+    @BeforeTemplate
+    @SuppressWarnings("EnumOrdinal" /* This violation will be rewritten. */)
+    Comparator<T> before() {
+      return comparingInt(v -> toEnumFunction(v).ordinal());
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    Comparator<T> after() {
+      return comparing(v -> toEnumFunction(v));
+    }
+  }
+
   /** Don't explicitly create {@link Comparator}s unnecessarily. */
   static final class ThenComparing<S, T extends Comparable<? super T>> {
     @BeforeTemplate
@@ -218,18 +245,77 @@ final class ComparatorRules {
     }
   }
 
+  /** Prefer {@link Collections#sort(List)} over more verbose alternatives. */
+  static final class CollectionsSort<T extends Comparable<? super T>> {
+    @BeforeTemplate
+    void before(List<T> collection) {
+      Collections.sort(collection, naturalOrder());
+    }
+
+    @AfterTemplate
+    void after(List<T> collection) {
+      Collections.sort(collection);
+    }
+  }
+
+  /** Prefer {@link Collections#min(Collection)} over more verbose alternatives. */
+  static final class CollectionsMin<T extends Comparable<? super T>> {
+    @BeforeTemplate
+    T before(Collection<T> collection) {
+      return Refaster.anyOf(
+          Collections.min(collection, naturalOrder()), Collections.max(collection, reverseOrder()));
+    }
+
+    @AfterTemplate
+    T after(Collection<T> collection) {
+      return Collections.min(collection);
+    }
+  }
+
   /**
    * Avoid unnecessary creation of a {@link Stream} to determine the minimum of a known collection
    * of values.
    */
-  static final class MinOfVarargs<T> {
+  static final class MinOfArray<S, T extends S> {
     @BeforeTemplate
-    T before(@Repeated T value, Comparator<T> cmp) {
+    T before(T[] array, Comparator<S> cmp) {
+      return Arrays.stream(array).min(cmp).orElseThrow();
+    }
+
+    @AfterTemplate
+    T after(T[] array, Comparator<S> cmp) {
+      return Collections.min(Arrays.asList(array), cmp);
+    }
+  }
+
+  /**
+   * Avoid unnecessary creation of a {@link Stream} to determine the minimum of a known collection
+   * of values.
+   */
+  static final class CollectionsMinWithComparator<S, T extends S> {
+    @BeforeTemplate
+    T before(Collection<T> collection, Comparator<S> cmp) {
+      return collection.stream().min(cmp).orElseThrow();
+    }
+
+    @AfterTemplate
+    T after(Collection<T> collection, Comparator<S> cmp) {
+      return Collections.min(collection, cmp);
+    }
+  }
+
+  /**
+   * Avoid unnecessary creation of a {@link Stream} to determine the minimum of a known collection
+   * of values.
+   */
+  static final class MinOfVarargs<S, T extends S> {
+    @BeforeTemplate
+    T before(@Repeated T value, Comparator<S> cmp) {
       return Stream.of(Refaster.asVarargs(value)).min(cmp).orElseThrow();
     }
 
     @AfterTemplate
-    T after(@Repeated T value, Comparator<T> cmp) {
+    T after(@Repeated T value, Comparator<S> cmp) {
       return Collections.min(Arrays.asList(value), cmp);
     }
   }
@@ -265,7 +351,7 @@ final class ComparatorRules {
   static final class MinOfPairCustomOrder<T> {
     @BeforeTemplate
     @SuppressWarnings("java:S1067" /* The conditional operators are independent. */)
-    T before(T value1, T value2, Comparator<T> cmp) {
+    T before(T value1, T value2, Comparator<? super T> cmp) {
       return Refaster.anyOf(
           cmp.compare(value1, value2) <= 0 ? value1 : value2,
           cmp.compare(value1, value2) > 0 ? value2 : value1,
@@ -280,23 +366,69 @@ final class ComparatorRules {
     }
 
     @AfterTemplate
-    T after(T value1, T value2, Comparator<T> cmp) {
+    T after(T value1, T value2, Comparator<? super T> cmp) {
       return Comparators.min(value1, value2, cmp);
     }
   }
 
+  /** Prefer {@link Collections#max(Collection)} over more verbose alternatives. */
+  static final class CollectionsMax<T extends Comparable<? super T>> {
+    @BeforeTemplate
+    T before(Collection<T> collection) {
+      return Refaster.anyOf(
+          Collections.max(collection, naturalOrder()), Collections.min(collection, reverseOrder()));
+    }
+
+    @AfterTemplate
+    T after(Collection<T> collection) {
+      return Collections.max(collection);
+    }
+  }
+
   /**
    * Avoid unnecessary creation of a {@link Stream} to determine the maximum of a known collection
    * of values.
    */
-  static final class MaxOfVarargs<T> {
+  static final class MaxOfArray<S, T extends S> {
     @BeforeTemplate
-    T before(@Repeated T value, Comparator<T> cmp) {
+    T before(T[] array, Comparator<S> cmp) {
+      return Arrays.stream(array).max(cmp).orElseThrow();
+    }
+
+    @AfterTemplate
+    T after(T[] array, Comparator<S> cmp) {
+      return Collections.max(Arrays.asList(array), cmp);
+    }
+  }
+
+  /**
+   * Avoid unnecessary creation of a {@link Stream} to determine the maximum of a known collection
+   * of values.
+   */
+  static final class CollectionsMaxWithComparator<S, T extends S> {
+    @BeforeTemplate
+    T before(Collection<T> collection, Comparator<S> cmp) {
+      return collection.stream().max(cmp).orElseThrow();
+    }
+
+    @AfterTemplate
+    T after(Collection<T> collection, Comparator<S> cmp) {
+      return Collections.max(collection, cmp);
+    }
+  }
+
+  /**
+   * Avoid unnecessary creation of a {@link Stream} to determine the maximum of a known collection
+   * of values.
+   */
+  static final class MaxOfVarargs<S, T extends S> {
+    @BeforeTemplate
+    T before(@Repeated T value, Comparator<S> cmp) {
       return Stream.of(Refaster.asVarargs(value)).max(cmp).orElseThrow();
     }
 
     @AfterTemplate
-    T after(@Repeated T value, Comparator<T> cmp) {
+    T after(@Repeated T value, Comparator<S> cmp) {
       return Collections.max(Arrays.asList(value), cmp);
     }
   }
@@ -332,7 +464,7 @@ final class ComparatorRules {
   static final class MaxOfPairCustomOrder<T> {
     @BeforeTemplate
     @SuppressWarnings("java:S1067" /* The conditional operators are independent. */)
-    T before(T value1, T value2, Comparator<T> cmp) {
+    T before(T value1, T value2, Comparator<? super T> cmp) {
       return Refaster.anyOf(
           cmp.compare(value1, value2) >= 0 ? value1 : value2,
           cmp.compare(value1, value2) < 0 ? value2 : value1,
@@ -347,7 +479,7 @@ final class ComparatorRules {
     }
 
     @AfterTemplate
-    T after(T value1, T value2, Comparator<T> cmp) {
+    T after(T value1, T value2, Comparator<? super T> cmp) {
       return Comparators.max(value1, value2, cmp);
     }
   }
@@ -383,4 +515,66 @@ final class ComparatorRules {
       return Comparators::max;
     }
   }
+
+  /**
+   * Prefer {@link Comparator#naturalOrder()} over {@link Comparator#reverseOrder()} where possible.
+   */
+  static final class MinByNaturalOrder<T extends Comparable<? super T>> {
+    @BeforeTemplate
+    Collector<T, ?, Optional<T>> before() {
+      return maxBy(reverseOrder());
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    Collector<T, ?, Optional<T>> after() {
+      return minBy(naturalOrder());
+    }
+  }
+
+  /**
+   * Prefer {@link Comparator#naturalOrder()} over {@link Comparator#reverseOrder()} where possible.
+   */
+  static final class MaxByNaturalOrder<T extends Comparable<? super T>> {
+    @BeforeTemplate
+    Collector<T, ?, Optional<T>> before() {
+      return minBy(reverseOrder());
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    Collector<T, ?, Optional<T>> after() {
+      return maxBy(naturalOrder());
+    }
+  }
+
+  /** Don't explicitly compare enums by their ordinal. */
+  static final class IsLessThan<E extends Enum<E>> {
+    @BeforeTemplate
+    @SuppressWarnings("EnumOrdinal" /* This violation will be rewritten. */)
+    boolean before(E value1, E value2) {
+      return value1.ordinal() < value2.ordinal();
+    }
+
+    @AfterTemplate
+    @AlsoNegation
+    boolean after(E value1, E value2) {
+      return value1.compareTo(value2) < 0;
+    }
+  }
+
+  /** Don't explicitly compare enums by their ordinal. */
+  static final class IsLessThanOrEqualTo<E extends Enum<E>> {
+    @BeforeTemplate
+    @SuppressWarnings("EnumOrdinal" /* This violation will be rewritten. */)
+    boolean before(E value1, E value2) {
+      return value1.ordinal() <= value2.ordinal();
+    }
+
+    @AfterTemplate
+    @AlsoNegation
+    boolean after(E value1, E value2) {
+      return value1.compareTo(value2) <= 0;
+    }
+  }
 }

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

@@ -1,5 +1,6 @@
 package tech.picnic.errorprone.refasterrules;
 
+import static java.util.function.Predicate.isEqual;
 import static java.util.function.Predicate.not;
 
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
@@ -19,9 +20,9 @@ import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 final class EqualityRules {
   private EqualityRules() {}
 
-  /** Prefer reference-based quality for enums. */
-  // Primitive value comparisons are not listed, because Error Prone flags those out of the box.
-  static final class PrimitiveOrReferenceEquality<T extends Enum<T>> {
+  /** Prefer reference-based equality for enums. */
+  // Primitive value comparisons are not matched, because Error Prone flags those out of the box.
+  static final class EnumReferenceEquality<T extends Enum<T>> {
     /**
      * Enums can be compared by reference. It is safe to do so even in the face of refactorings,
      * because if the type is ever converted to a non-enum, then Error-Prone will complain about any
@@ -30,8 +31,9 @@ final class EqualityRules {
     // XXX: This Refaster rule is the topic of https://github.com/google/error-prone/issues/559. We
     // work around the issue by selecting the "largest replacements". See the `Refaster` check.
     @BeforeTemplate
+    @SuppressWarnings("EnumOrdinal" /* This violation will be rewritten. */)
     boolean before(T a, T b) {
-      return Refaster.anyOf(a.equals(b), Objects.equals(a, b));
+      return Refaster.anyOf(a.equals(b), Objects.equals(a, b), a.ordinal() == b.ordinal());
     }
 
     @AfterTemplate
@@ -42,6 +44,20 @@ final class EqualityRules {
     }
   }
 
+  /** Prefer reference-based equality for enums. */
+  static final class EnumReferenceEqualityLambda<T extends Enum<T>> {
+    @BeforeTemplate
+    Predicate<T> before(T e) {
+      return Refaster.anyOf(isEqual(e), e::equals);
+    }
+
+    @AfterTemplate
+    @SuppressWarnings("java:S1698" /* Reference comparison is valid for enums. */)
+    Predicate<T> after(T e) {
+      return v -> v == e;
+    }
+  }
+
   /** Prefer {@link Object#equals(Object)} over the equivalent lambda function. */
   // XXX: As it stands, this rule is a special case of what `MethodReferenceUsage` tries to achieve.
   // If/when `MethodReferenceUsage` becomes production ready, we should simply drop this check.
@@ -157,23 +173,13 @@ final class EqualityRules {
   }
 
   /** Avoid contrived ways of handling {@code null} values during equality testing. */
-  static final class EqualsLhsNullable<T, S> {
+  static final class Equals<T, S> {
     @BeforeTemplate
     boolean before(T value1, S value2) {
-      return Optional.ofNullable(value1).equals(Optional.of(value2));
-    }
-
-    @AfterTemplate
-    boolean after(T value1, S value2) {
-      return value2.equals(value1);
-    }
-  }
-
-  /** Avoid contrived ways of handling {@code null} values during equality testing. */
-  static final class EqualsRhsNullable<T, S> {
-    @BeforeTemplate
-    boolean before(T value1, S value2) {
-      return Optional.of(value1).equals(Optional.ofNullable(value2));
+      return Refaster.anyOf(
+          Optional.of(value1).equals(Optional.of(value2)),
+          Optional.of(value1).equals(Optional.ofNullable(value2)),
+          Optional.ofNullable(value2).equals(Optional.of(value1)));
     }
 
     @AfterTemplate
@@ -183,7 +189,7 @@ final class EqualityRules {
   }
 
   /** Avoid contrived ways of handling {@code null} values during equality testing. */
-  static final class EqualsLhsAndRhsNullable<T, S> {
+  static final class ObjectsEquals<T, S> {
     @BeforeTemplate
     boolean before(T value1, S value2) {
       return Optional.ofNullable(value1).equals(Optional.ofNullable(value2));

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

@@ -2,12 +2,18 @@ package tech.picnic.errorprone.refasterrules;
 
 import static java.nio.charset.StandardCharsets.UTF_8;
 
+import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import com.google.errorprone.refaster.annotation.Repeated;
+import java.io.File;
 import java.io.IOException;
+import java.net.URI;
 import java.nio.charset.Charset;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.attribute.FileAttribute;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 
 /** Refaster rules related to expressions dealing with files. */
@@ -15,6 +21,49 @@ import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 final class FileRules {
   private FileRules() {}
 
+  /** Prefer the more idiomatic {@link Path#of(URI)} over {@link Paths#get(URI)}. */
+  static final class PathOfUri {
+    @BeforeTemplate
+    Path before(URI uri) {
+      return Paths.get(uri);
+    }
+
+    @AfterTemplate
+    Path after(URI uri) {
+      return Path.of(uri);
+    }
+  }
+
+  /**
+   * Prefer the more idiomatic {@link Path#of(String, String...)} over {@link Paths#get(String,
+   * String...)}.
+   */
+  static final class PathOfString {
+    @BeforeTemplate
+    Path before(String first, @Repeated String more) {
+      return Paths.get(first, more);
+    }
+
+    @AfterTemplate
+    Path after(String first, @Repeated String more) {
+      return Path.of(first, more);
+    }
+  }
+
+  /** Avoid redundant conversions from {@link Path} to {@link File}. */
+  // XXX: Review whether a rule such as this one is better handled by the `IdentityConversion` rule.
+  static final class PathInstance {
+    @BeforeTemplate
+    Path before(Path path) {
+      return path.toFile().toPath();
+    }
+
+    @AfterTemplate
+    Path after(Path path) {
+      return path;
+    }
+  }
+
   /** Prefer {@link Files#readString(Path, Charset)} over more contrived alternatives. */
   static final class FilesReadStringWithCharset {
     @BeforeTemplate
@@ -40,4 +89,44 @@ final class FileRules {
       return Files.readString(path);
     }
   }
+
+  /**
+   * Prefer {@link Files#createTempFile(String, String, FileAttribute[])} over alternatives that
+   * create files with more liberal permissions.
+   */
+  static final class FilesCreateTempFileToFile {
+    @BeforeTemplate
+    @SuppressWarnings({
+      "FilesCreateTempFileInCustomDirectoryToFile" /* This is a more specific template. */,
+      "java:S5443" /* This violation will be rewritten. */,
+      "key-to-resolve-AnnotationUseStyle-and-TrailingComment-check-conflict"
+    })
+    File before(String prefix, String suffix) throws IOException {
+      return Refaster.anyOf(
+          File.createTempFile(prefix, suffix), File.createTempFile(prefix, suffix, null));
+    }
+
+    @AfterTemplate
+    @SuppressWarnings(
+        "java:S5443" /* On POSIX systems the file will only have user read-write permissions. */)
+    File after(String prefix, String suffix) throws IOException {
+      return Files.createTempFile(prefix, suffix).toFile();
+    }
+  }
+
+  /**
+   * Prefer {@link Files#createTempFile(Path, String, String, FileAttribute[])} over alternatives
+   * that create files with more liberal permissions.
+   */
+  static final class FilesCreateTempFileInCustomDirectoryToFile {
+    @BeforeTemplate
+    File before(File directory, String prefix, String suffix) throws IOException {
+      return File.createTempFile(prefix, suffix, directory);
+    }
+
+    @AfterTemplate
+    File after(File directory, String prefix, String suffix) throws IOException {
+      return Files.createTempFile(directory.toPath(), prefix, suffix).toFile();
+    }
+  }
 }

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

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

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

@@ -118,17 +118,17 @@ final class ImmutableListRules {
    */
   static final class ImmutableListSortedCopyOfWithCustomComparator<T> {
     @BeforeTemplate
-    ImmutableList<T> before(Iterable<T> iterable, Comparator<T> cmp) {
+    ImmutableList<T> before(Comparator<T> cmp, Iterable<T> iterable) {
       return Streams.stream(iterable).sorted(cmp).collect(toImmutableList());
     }
 
     @BeforeTemplate
-    ImmutableList<T> before(Collection<T> iterable, Comparator<T> cmp) {
+    ImmutableList<T> before(Comparator<T> cmp, Collection<T> iterable) {
       return iterable.stream().sorted(cmp).collect(toImmutableList());
     }
 
     @AfterTemplate
-    ImmutableList<T> after(Collection<T> iterable, Comparator<? super T> cmp) {
+    ImmutableList<T> after(Comparator<? super T> cmp, Collection<T> iterable) {
       return ImmutableList.sortedCopyOf(cmp, iterable);
     }
   }

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

@@ -0,0 +1,63 @@
+package tech.picnic.errorprone.refasterrules;
+
+import com.google.common.io.ByteStreams;
+import com.google.errorprone.refaster.annotation.AfterTemplate;
+import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
+
+/** Refaster rules related to expressions dealing with {@link InputStream}s. */
+@OnlineDocumentation
+final class InputStreamRules {
+  private InputStreamRules() {}
+
+  static final class InputStreamTransferTo {
+    @BeforeTemplate
+    long before(InputStream in, OutputStream out) throws IOException {
+      return ByteStreams.copy(in, out);
+    }
+
+    @AfterTemplate
+    long after(InputStream in, OutputStream out) throws IOException {
+      return in.transferTo(out);
+    }
+  }
+
+  static final class InputStreamReadAllBytes {
+    @BeforeTemplate
+    byte[] before(InputStream in) throws IOException {
+      return ByteStreams.toByteArray(in);
+    }
+
+    @AfterTemplate
+    byte[] after(InputStream in) throws IOException {
+      return in.readAllBytes();
+    }
+  }
+
+  static final class InputStreamReadNBytes {
+    @BeforeTemplate
+    byte[] before(InputStream in, int n) throws IOException {
+      return ByteStreams.limit(in, n).readAllBytes();
+    }
+
+    @AfterTemplate
+    byte[] after(InputStream in, int n) throws IOException {
+      return in.readNBytes(n);
+    }
+  }
+
+  static final class InputStreamSkipNBytes {
+    @BeforeTemplate
+    void before(InputStream in, long n) throws IOException {
+      ByteStreams.skipFully(in, n);
+    }
+
+    @AfterTemplate
+    void after(InputStream in, long n) throws IOException {
+      in.skipNBytes(n);
+    }
+  }
+}

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

@@ -16,7 +16,6 @@ import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertThrowsExactly;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
-import com.google.common.collect.ImmutableSet;
 import com.google.errorprone.annotations.DoNotCall;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
@@ -27,6 +26,7 @@ import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.function.Executable;
 import org.junit.jupiter.api.function.ThrowingSupplier;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
+import tech.picnic.errorprone.refaster.annotation.TypeMigration;
 
 /**
  * Refaster rules to replace JUnit assertions with AssertJ equivalents.
@@ -41,34 +41,283 @@ import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 // `() -> toString()` match both `ThrowingSupplier` and `ThrowingCallable`, but `() -> "constant"`
 // is only compatible with the former.
 @OnlineDocumentation
+@TypeMigration(
+    of = Assertions.class,
+    unmigratedMethods = {
+      "assertAll(Collection<Executable>)",
+      "assertAll(Executable[])",
+      "assertAll(Stream<Executable>)",
+      "assertAll(String, Collection<Executable>)",
+      "assertAll(String, Executable[])",
+      "assertAll(String, Stream<Executable>)",
+      "assertArrayEquals(boolean[], boolean[])",
+      "assertArrayEquals(boolean[], boolean[], String)",
+      "assertArrayEquals(boolean[], boolean[], Supplier<String>)",
+      "assertArrayEquals(byte[], byte[])",
+      "assertArrayEquals(byte[], byte[], String)",
+      "assertArrayEquals(byte[], byte[], Supplier<String>)",
+      "assertArrayEquals(char[], char[])",
+      "assertArrayEquals(char[], char[], String)",
+      "assertArrayEquals(char[], char[], Supplier<String>)",
+      "assertArrayEquals(double[], double[])",
+      "assertArrayEquals(double[], double[], double)",
+      "assertArrayEquals(double[], double[], double, String)",
+      "assertArrayEquals(double[], double[], double, Supplier<String>)",
+      "assertArrayEquals(double[], double[], String)",
+      "assertArrayEquals(double[], double[], Supplier<String>)",
+      "assertArrayEquals(float[], float[])",
+      "assertArrayEquals(float[], float[], float)",
+      "assertArrayEquals(float[], float[], float, String)",
+      "assertArrayEquals(float[], float[], float, Supplier<String>)",
+      "assertArrayEquals(float[], float[], String)",
+      "assertArrayEquals(float[], float[], Supplier<String>)",
+      "assertArrayEquals(int[], int[])",
+      "assertArrayEquals(int[], int[], String)",
+      "assertArrayEquals(int[], int[], Supplier<String>)",
+      "assertArrayEquals(long[], long[])",
+      "assertArrayEquals(long[], long[], String)",
+      "assertArrayEquals(long[], long[], Supplier<String>)",
+      "assertArrayEquals(Object[], Object[])",
+      "assertArrayEquals(Object[], Object[], String)",
+      "assertArrayEquals(Object[], Object[], Supplier<String>)",
+      "assertArrayEquals(short[], short[])",
+      "assertArrayEquals(short[], short[], String)",
+      "assertArrayEquals(short[], short[], Supplier<String>)",
+      "assertEquals(Byte, Byte)",
+      "assertEquals(Byte, byte)",
+      "assertEquals(byte, Byte)",
+      "assertEquals(byte, byte)",
+      "assertEquals(Byte, Byte, String)",
+      "assertEquals(Byte, byte, String)",
+      "assertEquals(byte, Byte, String)",
+      "assertEquals(byte, byte, String)",
+      "assertEquals(Byte, Byte, Supplier<String>)",
+      "assertEquals(Byte, byte, Supplier<String>)",
+      "assertEquals(byte, Byte, Supplier<String>)",
+      "assertEquals(byte, byte, Supplier<String>)",
+      "assertEquals(char, char)",
+      "assertEquals(char, char, String)",
+      "assertEquals(char, char, Supplier<String>)",
+      "assertEquals(char, Character)",
+      "assertEquals(char, Character, String)",
+      "assertEquals(char, Character, Supplier<String>)",
+      "assertEquals(Character, char)",
+      "assertEquals(Character, char, String)",
+      "assertEquals(Character, char, Supplier<String>)",
+      "assertEquals(Character, Character)",
+      "assertEquals(Character, Character, String)",
+      "assertEquals(Character, Character, Supplier<String>)",
+      "assertEquals(Double, Double)",
+      "assertEquals(Double, double)",
+      "assertEquals(double, Double)",
+      "assertEquals(double, double)",
+      "assertEquals(double, double, double)",
+      "assertEquals(double, double, double, String)",
+      "assertEquals(double, double, double, Supplier<String>)",
+      "assertEquals(Double, Double, String)",
+      "assertEquals(Double, double, String)",
+      "assertEquals(double, Double, String)",
+      "assertEquals(double, double, String)",
+      "assertEquals(Double, Double, Supplier<String>)",
+      "assertEquals(Double, double, Supplier<String>)",
+      "assertEquals(double, Double, Supplier<String>)",
+      "assertEquals(double, double, Supplier<String>)",
+      "assertEquals(Float, Float)",
+      "assertEquals(Float, float)",
+      "assertEquals(float, Float)",
+      "assertEquals(float, float)",
+      "assertEquals(float, float, float)",
+      "assertEquals(float, float, float, String)",
+      "assertEquals(float, float, float, Supplier<String>)",
+      "assertEquals(Float, Float, String)",
+      "assertEquals(Float, float, String)",
+      "assertEquals(float, Float, String)",
+      "assertEquals(float, float, String)",
+      "assertEquals(Float, Float, Supplier<String>)",
+      "assertEquals(Float, float, Supplier<String>)",
+      "assertEquals(float, Float, Supplier<String>)",
+      "assertEquals(float, float, Supplier<String>)",
+      "assertEquals(int, int)",
+      "assertEquals(int, int, String)",
+      "assertEquals(int, int, Supplier<String>)",
+      "assertEquals(int, Integer)",
+      "assertEquals(int, Integer, String)",
+      "assertEquals(int, Integer, Supplier<String>)",
+      "assertEquals(Integer, int)",
+      "assertEquals(Integer, int, String)",
+      "assertEquals(Integer, int, Supplier<String>)",
+      "assertEquals(Integer, Integer)",
+      "assertEquals(Integer, Integer, String)",
+      "assertEquals(Integer, Integer, Supplier<String>)",
+      "assertEquals(Long, Long)",
+      "assertEquals(Long, long)",
+      "assertEquals(long, Long)",
+      "assertEquals(long, long)",
+      "assertEquals(Long, Long, String)",
+      "assertEquals(Long, long, String)",
+      "assertEquals(long, Long, String)",
+      "assertEquals(long, long, String)",
+      "assertEquals(Long, Long, Supplier<String>)",
+      "assertEquals(Long, long, Supplier<String>)",
+      "assertEquals(long, Long, Supplier<String>)",
+      "assertEquals(long, long, Supplier<String>)",
+      "assertEquals(Object, Object)",
+      "assertEquals(Object, Object, String)",
+      "assertEquals(Object, Object, Supplier<String>)",
+      "assertEquals(Short, Short)",
+      "assertEquals(Short, short)",
+      "assertEquals(short, Short)",
+      "assertEquals(short, short)",
+      "assertEquals(Short, Short, String)",
+      "assertEquals(Short, short, String)",
+      "assertEquals(short, Short, String)",
+      "assertEquals(short, short, String)",
+      "assertEquals(Short, Short, Supplier<String>)",
+      "assertEquals(Short, short, Supplier<String>)",
+      "assertEquals(short, Short, Supplier<String>)",
+      "assertEquals(short, short, Supplier<String>)",
+      "assertFalse(BooleanSupplier)",
+      "assertFalse(BooleanSupplier, String)",
+      "assertFalse(BooleanSupplier, Supplier<String>)",
+      "assertIterableEquals(Iterable<?>, Iterable<?>)",
+      "assertIterableEquals(Iterable<?>, Iterable<?>, String)",
+      "assertIterableEquals(Iterable<?>, Iterable<?>, Supplier<String>)",
+      "assertLinesMatch(List<String>, List<String>)",
+      "assertLinesMatch(List<String>, List<String>, String)",
+      "assertLinesMatch(List<String>, List<String>, Supplier<String>)",
+      "assertLinesMatch(Stream<String>, Stream<String>)",
+      "assertLinesMatch(Stream<String>, Stream<String>, String)",
+      "assertLinesMatch(Stream<String>, Stream<String>, Supplier<String>)",
+      "assertNotEquals(Byte, Byte)",
+      "assertNotEquals(Byte, byte)",
+      "assertNotEquals(byte, Byte)",
+      "assertNotEquals(byte, byte)",
+      "assertNotEquals(Byte, Byte, String)",
+      "assertNotEquals(Byte, byte, String)",
+      "assertNotEquals(byte, Byte, String)",
+      "assertNotEquals(byte, byte, String)",
+      "assertNotEquals(Byte, Byte, Supplier<String>)",
+      "assertNotEquals(Byte, byte, Supplier<String>)",
+      "assertNotEquals(byte, Byte, Supplier<String>)",
+      "assertNotEquals(byte, byte, Supplier<String>)",
+      "assertNotEquals(char, char)",
+      "assertNotEquals(char, char, String)",
+      "assertNotEquals(char, char, Supplier<String>)",
+      "assertNotEquals(char, Character)",
+      "assertNotEquals(char, Character, String)",
+      "assertNotEquals(char, Character, Supplier<String>)",
+      "assertNotEquals(Character, char)",
+      "assertNotEquals(Character, char, String)",
+      "assertNotEquals(Character, char, Supplier<String>)",
+      "assertNotEquals(Character, Character)",
+      "assertNotEquals(Character, Character, String)",
+      "assertNotEquals(Character, Character, Supplier<String>)",
+      "assertNotEquals(Double, Double)",
+      "assertNotEquals(Double, double)",
+      "assertNotEquals(double, Double)",
+      "assertNotEquals(double, double)",
+      "assertNotEquals(double, double, double)",
+      "assertNotEquals(double, double, double, String)",
+      "assertNotEquals(double, double, double, Supplier<String>)",
+      "assertNotEquals(Double, Double, String)",
+      "assertNotEquals(Double, double, String)",
+      "assertNotEquals(double, Double, String)",
+      "assertNotEquals(double, double, String)",
+      "assertNotEquals(Double, Double, Supplier<String>)",
+      "assertNotEquals(Double, double, Supplier<String>)",
+      "assertNotEquals(double, Double, Supplier<String>)",
+      "assertNotEquals(double, double, Supplier<String>)",
+      "assertNotEquals(Float, Float)",
+      "assertNotEquals(Float, float)",
+      "assertNotEquals(float, Float)",
+      "assertNotEquals(float, float)",
+      "assertNotEquals(float, float, float)",
+      "assertNotEquals(float, float, float, String)",
+      "assertNotEquals(float, float, float, Supplier<String>)",
+      "assertNotEquals(Float, Float, String)",
+      "assertNotEquals(Float, float, String)",
+      "assertNotEquals(float, Float, String)",
+      "assertNotEquals(float, float, String)",
+      "assertNotEquals(Float, Float, Supplier<String>)",
+      "assertNotEquals(Float, float, Supplier<String>)",
+      "assertNotEquals(float, Float, Supplier<String>)",
+      "assertNotEquals(float, float, Supplier<String>)",
+      "assertNotEquals(int, int)",
+      "assertNotEquals(int, int, String)",
+      "assertNotEquals(int, int, Supplier<String>)",
+      "assertNotEquals(int, Integer)",
+      "assertNotEquals(int, Integer, String)",
+      "assertNotEquals(int, Integer, Supplier<String>)",
+      "assertNotEquals(Integer, int)",
+      "assertNotEquals(Integer, int, String)",
+      "assertNotEquals(Integer, int, Supplier<String>)",
+      "assertNotEquals(Integer, Integer)",
+      "assertNotEquals(Integer, Integer, String)",
+      "assertNotEquals(Integer, Integer, Supplier<String>)",
+      "assertNotEquals(Long, Long)",
+      "assertNotEquals(Long, long)",
+      "assertNotEquals(long, Long)",
+      "assertNotEquals(long, long)",
+      "assertNotEquals(Long, Long, String)",
+      "assertNotEquals(Long, long, String)",
+      "assertNotEquals(long, Long, String)",
+      "assertNotEquals(long, long, String)",
+      "assertNotEquals(Long, Long, Supplier<String>)",
+      "assertNotEquals(Long, long, Supplier<String>)",
+      "assertNotEquals(long, Long, Supplier<String>)",
+      "assertNotEquals(long, long, Supplier<String>)",
+      "assertNotEquals(Object, Object)",
+      "assertNotEquals(Object, Object, String)",
+      "assertNotEquals(Object, Object, Supplier<String>)",
+      "assertNotEquals(Short, Short)",
+      "assertNotEquals(Short, short)",
+      "assertNotEquals(short, Short)",
+      "assertNotEquals(short, short)",
+      "assertNotEquals(Short, Short, String)",
+      "assertNotEquals(Short, short, String)",
+      "assertNotEquals(short, Short, String)",
+      "assertNotEquals(short, short, String)",
+      "assertNotEquals(Short, Short, Supplier<String>)",
+      "assertNotEquals(Short, short, Supplier<String>)",
+      "assertNotEquals(short, Short, Supplier<String>)",
+      "assertNotEquals(short, short, Supplier<String>)",
+      "assertTimeout(Duration, Executable)",
+      "assertTimeout(Duration, Executable, String)",
+      "assertTimeout(Duration, Executable, Supplier<String>)",
+      "assertTimeout(Duration, ThrowingSupplier<T>)",
+      "assertTimeout(Duration, ThrowingSupplier<T>, String)",
+      "assertTimeout(Duration, ThrowingSupplier<T>, Supplier<String>)",
+      "assertTimeoutPreemptively(Duration, Executable)",
+      "assertTimeoutPreemptively(Duration, Executable, String)",
+      "assertTimeoutPreemptively(Duration, Executable, Supplier<String>)",
+      "assertTimeoutPreemptively(Duration, ThrowingSupplier<T>)",
+      "assertTimeoutPreemptively(Duration, ThrowingSupplier<T>, String)",
+      "assertTimeoutPreemptively(Duration, ThrowingSupplier<T>, Supplier<String>)",
+      "assertTimeoutPreemptively(Duration, ThrowingSupplier<T>, Supplier<String>, TimeoutFailureFactory<E>)",
+      "assertTrue(BooleanSupplier)",
+      "assertTrue(BooleanSupplier, String)",
+      "assertTrue(BooleanSupplier, Supplier<String>)",
+      "fail(Supplier<String>)"
+    })
 final class JUnitToAssertJRules {
   private JUnitToAssertJRules() {}
 
-  public ImmutableSet<Object> elidedTypesAndStaticImports() {
-    return ImmutableSet.of(
-        Assertions.class,
-        assertDoesNotThrow(() -> null),
-        assertInstanceOf(null, null),
-        assertThrows(null, null),
-        assertThrowsExactly(null, null),
-        (Runnable) () -> assertFalse(true),
-        (Runnable) () -> assertNotNull(null),
-        (Runnable) () -> assertNotSame(null, null),
-        (Runnable) () -> assertNull(null),
-        (Runnable) () -> assertSame(null, null),
-        (Runnable) () -> assertTrue(true));
-  }
-
-  static final class ThrowNewAssertionError {
+  static final class Fail<T> {
     @BeforeTemplate
-    void before() {
-      Assertions.fail();
+    T before() {
+      return Assertions.fail();
     }
 
+    // XXX: Add `@UseImportPolicy(STATIC_IMPORT_ALWAYS)` once
+    // https://github.com/google/error-prone/pull/3584 is resolved. Until that time, statically
+    // importing AssertJ's `fail` is likely to clash with an existing static import of JUnit's
+    // `fail`. Note that combining Error Prone's `RemoveUnusedImports` and
+    // `UnnecessarilyFullyQualified` checks and our `StaticImport` check will anyway cause the
+    // method to be imported statically if possible; just in a less efficient manner.
     @AfterTemplate
     @DoNotCall
-    void after() {
-      throw new AssertionError();
+    T after() {
+      return fail();
     }
   }
 
@@ -78,8 +327,8 @@ final class JUnitToAssertJRules {
       return Assertions.fail(message);
     }
 
+    // XXX: Add `@UseImportPolicy(STATIC_IMPORT_ALWAYS)`. See `Fail` comment.
     @AfterTemplate
-    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     T after(String message) {
       return fail(message);
     }
@@ -91,23 +340,24 @@ final class JUnitToAssertJRules {
       return Assertions.fail(message, throwable);
     }
 
+    // XXX: Add `@UseImportPolicy(STATIC_IMPORT_ALWAYS)`. See `Fail` comment.
     @AfterTemplate
-    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     T after(String message, Throwable throwable) {
       return fail(message, throwable);
     }
   }
 
-  static final class FailWithThrowable {
+  static final class FailWithThrowable<T> {
     @BeforeTemplate
-    void before(Throwable throwable) {
-      Assertions.fail(throwable);
+    T before(Throwable throwable) {
+      return Assertions.fail(throwable);
     }
 
+    // XXX: Add `@UseImportPolicy(STATIC_IMPORT_ALWAYS)`. See `Fail` comment.
     @AfterTemplate
     @DoNotCall
-    void after(Throwable throwable) {
-      throw new AssertionError(throwable);
+    T after(Throwable throwable) {
+      return fail(throwable);
     }
   }
 
@@ -282,26 +532,26 @@ final class JUnitToAssertJRules {
 
   static final class AssertThatWithFailMessageStringIsSameAs {
     @BeforeTemplate
-    void before(Object actual, Object expected, String message) {
+    void before(Object actual, String message, Object expected) {
       assertSame(expected, actual, message);
     }
 
     @AfterTemplate
     @UseImportPolicy(STATIC_IMPORT_ALWAYS)
-    void after(Object actual, Object expected, String message) {
+    void after(Object actual, String message, Object expected) {
       assertThat(actual).withFailMessage(message).isSameAs(expected);
     }
   }
 
   static final class AssertThatWithFailMessageSupplierIsSameAs {
     @BeforeTemplate
-    void before(Object actual, Object expected, Supplier<String> supplier) {
+    void before(Object actual, Supplier<String> supplier, Object expected) {
       assertSame(expected, actual, supplier);
     }
 
     @AfterTemplate
     @UseImportPolicy(STATIC_IMPORT_ALWAYS)
-    void after(Object actual, Object expected, Supplier<String> supplier) {
+    void after(Object actual, Supplier<String> supplier, Object expected) {
       assertThat(actual).withFailMessage(supplier).isSameAs(expected);
     }
   }
@@ -321,26 +571,26 @@ final class JUnitToAssertJRules {
 
   static final class AssertThatWithFailMessageStringIsNotSameAs {
     @BeforeTemplate
-    void before(Object actual, Object expected, String message) {
+    void before(Object actual, String message, Object expected) {
       assertNotSame(expected, actual, message);
     }
 
     @AfterTemplate
     @UseImportPolicy(STATIC_IMPORT_ALWAYS)
-    void after(Object actual, Object expected, String message) {
+    void after(Object actual, String message, Object expected) {
       assertThat(actual).withFailMessage(message).isNotSameAs(expected);
     }
   }
 
   static final class AssertThatWithFailMessageSupplierIsNotSameAs {
     @BeforeTemplate
-    void before(Object actual, Object expected, Supplier<String> supplier) {
+    void before(Object actual, Supplier<String> supplier, Object expected) {
       assertNotSame(expected, actual, supplier);
     }
 
     @AfterTemplate
     @UseImportPolicy(STATIC_IMPORT_ALWAYS)
-    void after(Object actual, Object expected, Supplier<String> supplier) {
+    void after(Object actual, Supplier<String> supplier, Object expected) {
       assertThat(actual).withFailMessage(supplier).isNotSameAs(expected);
     }
   }
@@ -361,13 +611,13 @@ final class JUnitToAssertJRules {
   static final class AssertThatThrownByWithFailMessageStringIsExactlyInstanceOf<
       T extends Throwable> {
     @BeforeTemplate
-    void before(Executable throwingCallable, Class<T> clazz, String message) {
+    void before(Executable throwingCallable, String message, Class<T> clazz) {
       assertThrowsExactly(clazz, throwingCallable, message);
     }
 
     @AfterTemplate
     @UseImportPolicy(STATIC_IMPORT_ALWAYS)
-    void after(ThrowingCallable throwingCallable, Class<T> clazz, String message) {
+    void after(ThrowingCallable throwingCallable, String message, Class<T> clazz) {
       assertThatThrownBy(throwingCallable).withFailMessage(message).isExactlyInstanceOf(clazz);
     }
   }
@@ -375,13 +625,13 @@ final class JUnitToAssertJRules {
   static final class AssertThatThrownByWithFailMessageSupplierIsExactlyInstanceOf<
       T extends Throwable> {
     @BeforeTemplate
-    void before(Executable throwingCallable, Class<T> clazz, Supplier<String> supplier) {
+    void before(Executable throwingCallable, Supplier<String> supplier, Class<T> clazz) {
       assertThrowsExactly(clazz, throwingCallable, supplier);
     }
 
     @AfterTemplate
     @UseImportPolicy(STATIC_IMPORT_ALWAYS)
-    void after(ThrowingCallable throwingCallable, Class<T> clazz, Supplier<String> supplier) {
+    void after(ThrowingCallable throwingCallable, Supplier<String> supplier, Class<T> clazz) {
       assertThatThrownBy(throwingCallable).withFailMessage(supplier).isExactlyInstanceOf(clazz);
     }
   }
@@ -401,26 +651,26 @@ final class JUnitToAssertJRules {
 
   static final class AssertThatThrownByWithFailMessageStringIsInstanceOf<T extends Throwable> {
     @BeforeTemplate
-    void before(Executable throwingCallable, Class<T> clazz, String message) {
+    void before(Executable throwingCallable, String message, Class<T> clazz) {
       assertThrows(clazz, throwingCallable, message);
     }
 
     @AfterTemplate
     @UseImportPolicy(STATIC_IMPORT_ALWAYS)
-    void after(ThrowingCallable throwingCallable, Class<T> clazz, String message) {
+    void after(ThrowingCallable throwingCallable, String message, Class<T> clazz) {
       assertThatThrownBy(throwingCallable).withFailMessage(message).isInstanceOf(clazz);
     }
   }
 
   static final class AssertThatThrownByWithFailMessageSupplierIsInstanceOf<T extends Throwable> {
     @BeforeTemplate
-    void before(Executable throwingCallable, Class<T> clazz, Supplier<String> supplier) {
+    void before(Executable throwingCallable, Supplier<String> supplier, Class<T> clazz) {
       assertThrows(clazz, throwingCallable, supplier);
     }
 
     @AfterTemplate
     @UseImportPolicy(STATIC_IMPORT_ALWAYS)
-    void after(ThrowingCallable throwingCallable, Class<T> clazz, Supplier<String> supplier) {
+    void after(ThrowingCallable throwingCallable, Supplier<String> supplier, Class<T> clazz) {
       assertThatThrownBy(throwingCallable).withFailMessage(supplier).isInstanceOf(clazz);
     }
   }
@@ -494,26 +744,26 @@ final class JUnitToAssertJRules {
 
   static final class AssertThatWithFailMessageStringIsInstanceOf<T> {
     @BeforeTemplate
-    void before(Object actual, Class<T> clazz, String message) {
+    void before(Object actual, String message, Class<T> clazz) {
       assertInstanceOf(clazz, actual, message);
     }
 
     @AfterTemplate
     @UseImportPolicy(STATIC_IMPORT_ALWAYS)
-    void after(Object actual, Class<T> clazz, String message) {
+    void after(Object actual, String message, Class<T> clazz) {
       assertThat(actual).withFailMessage(message).isInstanceOf(clazz);
     }
   }
 
   static final class AssertThatWithFailMessageSupplierIsInstanceOf<T> {
     @BeforeTemplate
-    void before(Object actual, Class<T> clazz, Supplier<String> supplier) {
+    void before(Object actual, Supplier<String> supplier, Class<T> clazz) {
       assertInstanceOf(clazz, actual, supplier);
     }
 
     @AfterTemplate
     @UseImportPolicy(STATIC_IMPORT_ALWAYS)
-    void after(Object actual, Class<T> clazz, Supplier<String> supplier) {
+    void after(Object actual, Supplier<String> supplier, Class<T> clazz) {
       assertThat(actual).withFailMessage(supplier).isInstanceOf(clazz);
     }
   }

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

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

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

@@ -6,7 +6,9 @@ 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 java.util.Map;
 import java.util.Set;
+import java.util.stream.Stream;
 import org.jspecify.annotations.Nullable;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 
@@ -28,6 +30,21 @@ final class MultimapRules {
     }
   }
 
+  /** Prefer {@link Multimap#isEmpty()} over more contrived alternatives. */
+  static final class MultimapIsEmpty<K, V> {
+    @BeforeTemplate
+    boolean before(Multimap<K, V> multimap) {
+      return Refaster.anyOf(
+              multimap.keySet(), multimap.keys(), multimap.values(), multimap.entries())
+          .isEmpty();
+    }
+
+    @AfterTemplate
+    boolean after(Multimap<K, V> multimap) {
+      return multimap.isEmpty();
+    }
+  }
+
   /** Prefer {@link Multimap#size()} over more contrived alternatives. */
   static final class MultimapSize<K, V> {
     @BeforeTemplate
@@ -41,6 +58,32 @@ final class MultimapRules {
     }
   }
 
+  /** Prefer {@link Multimap#containsKey(Object)} over more contrived alternatives. */
+  static final class MultimapContainsKey<K, V, T> {
+    @BeforeTemplate
+    boolean before(Multimap<K, V> multimap, T key) {
+      return Refaster.anyOf(multimap.keySet(), multimap.keys()).contains(key);
+    }
+
+    @AfterTemplate
+    boolean after(Multimap<K, V> multimap, T key) {
+      return multimap.containsKey(key);
+    }
+  }
+
+  /** Prefer {@link Multimap#containsValue(Object)} over more contrived alternatives. */
+  static final class MultimapContainsValue<K, V, T> {
+    @BeforeTemplate
+    boolean before(Multimap<K, V> multimap, T value) {
+      return multimap.values().contains(value);
+    }
+
+    @AfterTemplate
+    boolean after(Multimap<K, V> multimap, T value) {
+      return multimap.containsValue(value);
+    }
+  }
+
   /**
    * Prefer {@link Multimap#get(Object)} over more contrived alternatives.
    *
@@ -59,4 +102,30 @@ final class MultimapRules {
       return multimap.get(key);
     }
   }
+
+  /** Don't unnecessarily use {@link Multimap#entries()}. */
+  static final class MultimapKeysStream<K, V> {
+    @BeforeTemplate
+    Stream<K> before(Multimap<K, V> multimap) {
+      return multimap.entries().stream().map(Map.Entry::getKey);
+    }
+
+    @AfterTemplate
+    Stream<K> after(Multimap<K, V> multimap) {
+      return multimap.keys().stream();
+    }
+  }
+
+  /** Don't unnecessarily use {@link Multimap#entries()}. */
+  static final class MultimapValuesStream<K, V> {
+    @BeforeTemplate
+    Stream<V> before(Multimap<K, V> multimap) {
+      return multimap.entries().stream().map(Map.Entry::getValue);
+    }
+
+    @AfterTemplate
+    Stream<V> after(Multimap<K, V> multimap) {
+      return multimap.values().stream();
+    }
+  }
 }

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

@@ -20,13 +20,26 @@ import java.util.function.Supplier;
 import java.util.stream.Stream;
 import org.jspecify.annotations.Nullable;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
-import tech.picnic.errorprone.refaster.matchers.IsLikelyTrivialComputation;
+import tech.picnic.errorprone.refaster.matchers.RequiresComputation;
 
 /** Refaster rules related to expressions dealing with {@link Optional}s. */
 @OnlineDocumentation
 final class OptionalRules {
   private OptionalRules() {}
 
+  /** Prefer {@link Optional#empty()} over the more contrived alternative. */
+  static final class OptionalEmpty<T> {
+    @BeforeTemplate
+    Optional<T> before() {
+      return Optional.ofNullable(null);
+    }
+
+    @AfterTemplate
+    Optional<T> after() {
+      return Optional.empty();
+    }
+  }
+
   static final class OptionalOfNullable<T> {
     // XXX: Refaster should be smart enough to also rewrite occurrences in which there are
     // parentheses around the null check, but that's currently not the case. Try to fix that.
@@ -242,24 +255,21 @@ final class OptionalRules {
   }
 
   /**
-   * Prefer {@link Optional#orElseGet(Supplier)} over {@link Optional#orElse(Object)} if the
-   * fallback value is not the result of a trivial computation.
+   * Prefer {@link Optional#orElse(Object)} over {@link Optional#orElseGet(Supplier)} if the
+   * fallback value does not require non-trivial computation.
    */
-  // XXX: This rule may introduce a compilation error: the `value` expression may reference a
-  // non-effectively final variable, which is not allowed in the replacement lambda expression.
-  // Review whether a `@Matcher` can be used to avoid this.
-  // XXX: Once `MethodReferenceUsage` is "production ready", replace
-  // `@NotMatches(IsLikelyTrivialComputation.class)` with `@Matches(RequiresComputation.class)` (and
-  // reimplement the matcher accordingly).
-  static final class OptionalOrElseGet<T> {
+  // XXX: This rule is the counterpart to the `OptionalOrElseGet` bug checker. Once the
+  // `MethodReferenceUsage` bug checker is "production ready", that bug checker may similarly be
+  // replaced with a Refaster rule.
+  static final class OptionalOrElse<T> {
     @BeforeTemplate
-    T before(Optional<T> optional, @NotMatches(IsLikelyTrivialComputation.class) T value) {
-      return optional.orElse(value);
+    T before(Optional<T> optional, @NotMatches(RequiresComputation.class) T value) {
+      return optional.orElseGet(() -> value);
     }
 
     @AfterTemplate
     T after(Optional<T> optional, T value) {
-      return optional.orElseGet(() -> value);
+      return optional.orElse(value);
     }
   }
 
@@ -360,7 +370,12 @@ final class OptionalRules {
   /** Prefer {@link Optional#or(Supplier)} over more verbose alternatives. */
   static final class OptionalOrOtherOptional<T> {
     @BeforeTemplate
-    @SuppressWarnings("NestedOptionals" /* Auto-fix for the `NestedOptionals` check. */)
+    @SuppressWarnings({
+      "LexicographicalAnnotationAttributeListing" /* `key-*` entry must remain last. */,
+      "NestedOptionals" /* This violation will be rewritten. */,
+      "OptionalOrElse" /* Parameters represent expressions that may require computation. */,
+      "key-to-resolve-AnnotationUseStyle-and-TrailingComment-check-conflict"
+    })
     Optional<T> before(Optional<T> optional1, Optional<T> optional2) {
       // XXX: Note that rewriting the first and third variant will change the code's behavior if
       // `optional2` has side-effects.
@@ -386,8 +401,13 @@ final class OptionalRules {
    */
   static final class OptionalIdentity<T> {
     @BeforeTemplate
+    @SuppressWarnings("NestedOptionals")
     Optional<T> before(Optional<T> optional, Comparator<? super T> comparator) {
       return Refaster.anyOf(
+          optional.or(Refaster.anyOf(() -> Optional.empty(), Optional::empty)),
+          optional
+              .map(Optional::of)
+              .orElseGet(Refaster.anyOf(() -> Optional.empty(), Optional::empty)),
           optional.stream().findFirst(),
           optional.stream().findAny(),
           optional.stream().min(comparator),
@@ -441,9 +461,7 @@ final class OptionalRules {
   static final class OptionalStream<T> {
     @BeforeTemplate
     Stream<T> before(Optional<T> optional) {
-      return Refaster.anyOf(
-          optional.map(Stream::of).orElse(Stream.empty()),
-          optional.map(Stream::of).orElseGet(Stream::empty));
+      return optional.map(Stream::of).orElseGet(Stream::empty);
     }
 
     @AfterTemplate

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

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

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

@@ -3,13 +3,17 @@ package tech.picnic.errorprone.refasterrules;
 import static com.google.common.collect.ImmutableList.toImmutableList;
 import static com.google.common.collect.ImmutableSet.toImmutableSet;
 import static com.google.common.collect.MoreCollectors.toOptional;
-import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
 import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
+import static java.util.Comparator.naturalOrder;
+import static java.util.Comparator.reverseOrder;
 import static java.util.function.Function.identity;
+import static java.util.stream.Collectors.maxBy;
+import static java.util.stream.Collectors.minBy;
 import static java.util.stream.Collectors.toCollection;
 import static org.assertj.core.api.Assertions.assertThat;
 import static reactor.function.TupleUtils.function;
 
+import com.github.benmanes.caffeine.cache.AsyncLoadingCache;
 import com.google.common.collect.ImmutableCollection;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
@@ -30,6 +34,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Optional;
 import java.util.concurrent.Callable;
+import java.util.concurrent.CompletableFuture;
 import java.util.function.BiConsumer;
 import java.util.function.BiFunction;
 import java.util.function.Consumer;
@@ -37,17 +42,18 @@ import java.util.function.Function;
 import java.util.function.Predicate;
 import java.util.function.Supplier;
 import java.util.stream.Collector;
+import java.util.stream.Stream;
 import org.jspecify.annotations.Nullable;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
+import reactor.math.MathFlux;
 import reactor.test.StepVerifier;
 import reactor.test.publisher.PublisherProbe;
 import reactor.util.context.Context;
 import reactor.util.function.Tuple2;
 import tech.picnic.errorprone.refaster.annotation.Description;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
-import tech.picnic.errorprone.refaster.annotation.Severity;
 import tech.picnic.errorprone.refaster.matchers.IsEmpty;
 import tech.picnic.errorprone.refaster.matchers.IsIdentityOperation;
 import tech.picnic.errorprone.refaster.matchers.ThrowsCheckedException;
@@ -100,7 +106,7 @@ final class ReactorRules {
   }
 
   /** Prefer {@link Mono#justOrEmpty(Object)} over more contrived alternatives. */
-  static final class MonoJustOrEmptyObject<@Nullable T> {
+  static final class MonoJustOrEmptyObject<T extends @Nullable Object> {
     @BeforeTemplate
     Mono<T> before(T value) {
       return Mono.justOrEmpty(Optional.ofNullable(value));
@@ -375,30 +381,23 @@ final class ReactorRules {
   }
 
   /**
-   * Prefer {@link Flux#take(long, boolean)} over {@link Flux#take(long)}.
+   * Prefer {@link Flux#take(long)} over {@link Flux#take(long, boolean)} where relevant.
    *
    * <p>In Reactor versions prior to 3.5.0, {@code Flux#take(long)} makes an unbounded request
-   * upstream, and is equivalent to {@code Flux#take(long, false)}. In 3.5.0, the behavior of {@code
-   * Flux#take(long)} will change to that of {@code Flux#take(long, true)}.
-   *
-   * <p>The intent with this Refaster rule is to get the new behavior before upgrading to Reactor
-   * 3.5.0.
+   * upstream, and is equivalent to {@code Flux#take(long, false)}. From version 3.5.0 onwards, the
+   * behavior of {@code Flux#take(long)} instead matches {@code Flux#take(long, true)}.
    */
-  // XXX: Drop this rule some time after upgrading to Reactor 3.6.0, or introduce a way to apply
-  // this rule only when an older version of Reactor is on the classpath.
-  // XXX: Once Reactor 3.6.0 is out, introduce a rule that rewrites code in the opposite direction.
   @Description(
-      "Prior to Reactor 3.5.0, `take(n)` requests and unbounded number of elements upstream.")
-  @Severity(WARNING)
+      "From Reactor 3.5.0 onwards, `take(n)` no longer requests an unbounded number of elements upstream.")
   static final class FluxTake<T> {
     @BeforeTemplate
     Flux<T> before(Flux<T> flux, long n) {
-      return flux.take(n);
+      return flux.take(n, /* limitRequest= */ true);
     }
 
     @AfterTemplate
     Flux<T> after(Flux<T> flux, long n) {
-      return flux.take(n, /* limitRequest= */ true);
+      return flux.take(n);
     }
   }
 
@@ -437,10 +436,12 @@ final class ReactorRules {
   static final class FluxEmpty<T, S extends Comparable<? super S>> {
     @BeforeTemplate
     Flux<T> before(
-        int prefetch,
         Function<? super Object[], ? extends T> combinator,
+        int prefetch,
         Comparator<? super T> comparator) {
       return Refaster.anyOf(
+          Flux.zip(combinator),
+          Flux.zip(combinator, prefetch),
           Flux.concat(),
           Flux.concatDelayError(),
           Flux.firstWithSignal(),
@@ -456,13 +457,11 @@ final class ReactorRules {
           Flux.mergePriorityDelayError(prefetch, comparator),
           Flux.mergeSequential(),
           Flux.mergeSequential(prefetch),
-          Flux.mergeSequentialDelayError(prefetch),
-          Flux.zip(combinator),
-          Flux.zip(combinator, prefetch));
+          Flux.mergeSequentialDelayError(prefetch));
     }
 
     @BeforeTemplate
-    Flux<T> before(int prefetch, Function<Object[], T> combinator) {
+    Flux<T> before(Function<Object[], T> combinator, int prefetch) {
       return Refaster.anyOf(
           Flux.combineLatest(combinator), Flux.combineLatest(combinator, prefetch));
     }
@@ -484,15 +483,20 @@ final class ReactorRules {
   }
 
   /** Prefer {@link Flux#just(Object)} over more contrived alternatives. */
-  static final class FluxJust {
+  static final class FluxJust<T> {
     @BeforeTemplate
-    Flux<Integer> before(int start) {
-      return Flux.range(start, 1);
+    Flux<Integer> before(int value) {
+      return Flux.range(value, 1);
+    }
+
+    @BeforeTemplate
+    Flux<T> before(T value) {
+      return Mono.just(value).repeat().take(1);
     }
 
     @AfterTemplate
-    Flux<Integer> after(int start) {
-      return Flux.just(start);
+    Flux<T> after(T value) {
+      return Flux.just(value);
     }
   }
 
@@ -561,6 +565,7 @@ final class ReactorRules {
         @Matches(IsIdentityOperation.class)
             Function<? super P, ? extends Publisher<? extends S>> identityOperation) {
       return Refaster.anyOf(
+          flux.concatMap(function, 0),
           flux.flatMap(function, 1),
           flux.flatMapSequential(function, 1),
           flux.map(function).concatMap(identityOperation));
@@ -596,6 +601,11 @@ final class ReactorRules {
 
   /** Avoid contrived alternatives to {@link Mono#flatMapIterable(Function)}. */
   static final class MonoFlatMapIterable<T, S, I extends Iterable<? extends S>> {
+    @BeforeTemplate
+    Flux<S> before(Mono<T> mono, Function<? super T, I> function) {
+      return mono.map(function).flatMapMany(Flux::fromIterable);
+    }
+
     @BeforeTemplate
     Flux<S> before(
         Mono<T> mono,
@@ -608,7 +618,7 @@ final class ReactorRules {
     }
 
     @AfterTemplate
-    Flux<S> after(Mono<T> mono, Function<? super T, ? extends Iterable<? extends S>> function) {
+    Flux<S> after(Mono<T> mono, Function<? super T, I> function) {
       return mono.flatMapIterable(function);
     }
   }
@@ -727,7 +737,7 @@ final class ReactorRules {
     abstract S transformation(@MayOptionallyUse T value);
 
     @BeforeTemplate
-    Flux<S> before(Flux<T> flux, boolean delayUntilEnd, int maxConcurrency, int prefetch) {
+    Flux<S> before(Flux<T> flux, int prefetch, boolean delayUntilEnd, int maxConcurrency) {
       return Refaster.anyOf(
           flux.concatMap(x -> Mono.just(transformation(x))),
           flux.concatMap(x -> Flux.just(transformation(x))),
@@ -795,7 +805,7 @@ final class ReactorRules {
 
     @BeforeTemplate
     @SuppressWarnings("java:S138" /* Method is long, but not complex. */)
-    Publisher<S> before(Flux<T> flux, boolean delayUntilEnd, int maxConcurrency, int prefetch) {
+    Publisher<S> before(Flux<T> flux, int prefetch, boolean delayUntilEnd, int maxConcurrency) {
       return Refaster.anyOf(
           flux.concatMap(
               x ->
@@ -950,11 +960,12 @@ final class ReactorRules {
     }
   }
 
-  /** Avoid vacuous invocations of {@link Mono#ignoreElement()}. */
+  /** Avoid vacuous operations prior to invocation of {@link Mono#thenMany(Publisher)}. */
   static final class MonoThenMany<T, S> {
     @BeforeTemplate
     Flux<S> before(Mono<T> mono, Publisher<S> publisher) {
-      return mono.ignoreElement().thenMany(publisher);
+      return Refaster.anyOf(
+          mono.ignoreElement().thenMany(publisher), mono.flux().thenMany(publisher));
     }
 
     @AfterTemplate
@@ -992,11 +1003,11 @@ final class ReactorRules {
     }
   }
 
-  /** Avoid vacuous invocations of {@link Mono#ignoreElement()}. */
+  /** Avoid vacuous operations prior to invocation of {@link Mono#then(Mono)}. */
   static final class MonoThenMono<T, S> {
     @BeforeTemplate
     Mono<S> before(Mono<T> mono1, Mono<S> mono2) {
-      return mono1.ignoreElement().then(mono2);
+      return Refaster.anyOf(mono1.ignoreElement().then(mono2), mono1.flux().then(mono2));
     }
 
     @BeforeTemplate
@@ -1031,12 +1042,15 @@ final class ReactorRules {
   /** Prefer {@link Mono#singleOptional()} over more contrived alternatives. */
   // XXX: Consider creating a plugin that flags/discourages `Mono<Optional<T>>` method return
   // types, just as we discourage nullable `Boolean`s and `Optional`s.
+  // XXX: The `mono.transform(Mono::singleOptional)` replacement is a special case of a more general
+  // rule. Consider introducing an Error Prone check for this.
   static final class MonoSingleOptional<T> {
     @BeforeTemplate
     Mono<Optional<T>> before(Mono<T> mono) {
       return Refaster.anyOf(
           mono.flux().collect(toOptional()),
-          mono.map(Optional::of).defaultIfEmpty(Optional.empty()));
+          mono.map(Optional::of).defaultIfEmpty(Optional.empty()),
+          mono.transform(Mono::singleOptional));
     }
 
     @AfterTemplate
@@ -1125,9 +1139,9 @@ final class ReactorRules {
         Function<? super S, P> function,
         @Matches(IsIdentityOperation.class)
             Function<? super P, ? extends Publisher<? extends T>> identityOperation,
+        int prefetch,
         boolean delayUntilEnd,
-        int maxConcurrency,
-        int prefetch) {
+        int maxConcurrency) {
       return Refaster.anyOf(
           mono.map(function).flatMapMany(identityOperation),
           mono.flux().concatMap(function),
@@ -1191,6 +1205,26 @@ final class ReactorRules {
     }
   }
 
+  /** Prefer {@link Flux#fromIterable(Iterable)} over less efficient alternatives. */
+  // XXX: Once the `FluxFromStreamSupplier` rule is constrained using
+  // `@NotMatches(IsIdentityOperation.class)`, this rule should also cover
+  // `Flux.fromStream(collection.stream())`.
+  static final class FluxFromIterable<T> {
+    // XXX: Once the `MethodReferenceUsage` check is generally enabled, drop the second
+    // `Refaster.anyOf` variant.
+    @BeforeTemplate
+    Flux<T> before(Collection<T> collection) {
+      return Flux.fromStream(
+          Refaster.<Supplier<Stream<? extends T>>>anyOf(
+              collection::stream, () -> collection.stream()));
+    }
+
+    @AfterTemplate
+    Flux<T> after(Collection<T> collection) {
+      return Flux.fromIterable(collection);
+    }
+  }
+
   /**
    * Prefer {@link Flux#count()} followed by a conversion from {@code long} to {@code int} over
    * collecting into a list and counting its elements.
@@ -1579,6 +1613,107 @@ final class ReactorRules {
     }
   }
 
+  /** Prefer {@link Flux#sort()} over more verbose alternatives. */
+  static final class FluxSort<T extends Comparable<? super T>> {
+    @BeforeTemplate
+    Flux<T> before(Flux<T> flux) {
+      return flux.sort(naturalOrder());
+    }
+
+    @AfterTemplate
+    Flux<T> after(Flux<T> flux) {
+      return flux.sort();
+    }
+  }
+
+  /** Prefer {@link MathFlux#min(Publisher)} over less efficient alternatives. */
+  static final class FluxTransformMin<T extends Comparable<? super T>> {
+    @BeforeTemplate
+    Mono<T> before(Flux<T> flux) {
+      return flux.sort().next();
+    }
+
+    @AfterTemplate
+    Mono<T> after(Flux<T> flux) {
+      return flux.transform(MathFlux::min).singleOrEmpty();
+    }
+  }
+
+  /**
+   * Prefer {@link MathFlux#min(Publisher, Comparator)} over less efficient or more verbose
+   * alternatives.
+   */
+  static final class FluxTransformMinWithComparator<T extends Comparable<? super T>> {
+    @BeforeTemplate
+    Mono<T> before(Flux<T> flux, Comparator<? super T> cmp) {
+      return Refaster.anyOf(
+          flux.sort(cmp).next(), flux.collect(minBy(cmp)).flatMap(Mono::justOrEmpty));
+    }
+
+    @AfterTemplate
+    Mono<T> after(Flux<T> flux, Comparator<? super T> cmp) {
+      return flux.transform(f -> MathFlux.min(f, cmp)).singleOrEmpty();
+    }
+  }
+
+  /** Prefer {@link MathFlux#max(Publisher)} over less efficient alternatives. */
+  static final class FluxTransformMax<T extends Comparable<? super T>> {
+    @BeforeTemplate
+    Mono<T> before(Flux<T> flux) {
+      return flux.sort().last();
+    }
+
+    @AfterTemplate
+    Mono<T> after(Flux<T> flux) {
+      return flux.transform(MathFlux::max).singleOrEmpty();
+    }
+  }
+
+  /**
+   * Prefer {@link MathFlux#max(Publisher, Comparator)} over less efficient or more verbose
+   * alternatives.
+   */
+  static final class FluxTransformMaxWithComparator<T extends Comparable<? super T>> {
+    @BeforeTemplate
+    Mono<T> before(Flux<T> flux, Comparator<? super T> cmp) {
+      return Refaster.anyOf(
+          flux.sort(cmp).last(), flux.collect(maxBy(cmp)).flatMap(Mono::justOrEmpty));
+    }
+
+    @AfterTemplate
+    Mono<T> after(Flux<T> flux, Comparator<? super T> cmp) {
+      return flux.transform(f -> MathFlux.max(f, cmp)).singleOrEmpty();
+    }
+  }
+
+  /** Prefer {@link MathFlux#min(Publisher)} over more contrived alternatives. */
+  static final class MathFluxMin<T extends Comparable<? super T>> {
+    @BeforeTemplate
+    Mono<T> before(Publisher<T> publisher) {
+      return Refaster.anyOf(
+          MathFlux.min(publisher, naturalOrder()), MathFlux.max(publisher, reverseOrder()));
+    }
+
+    @AfterTemplate
+    Mono<T> after(Publisher<T> publisher) {
+      return MathFlux.min(publisher);
+    }
+  }
+
+  /** Prefer {@link MathFlux#max(Publisher)} over more contrived alternatives. */
+  static final class MathFluxMax<T extends Comparable<? super T>> {
+    @BeforeTemplate
+    Mono<T> before(Publisher<T> publisher) {
+      return Refaster.anyOf(
+          MathFlux.min(publisher, reverseOrder()), MathFlux.max(publisher, naturalOrder()));
+    }
+
+    @AfterTemplate
+    Mono<T> after(Publisher<T> publisher) {
+      return MathFlux.max(publisher);
+    }
+  }
+
   /** Prefer {@link reactor.util.context.Context#empty()}} over more verbose alternatives. */
   // XXX: Introduce Refaster rules or a `BugChecker` that maps `(Immutable)Map.of(k, v)` to
   // `Context.of(k, v)` and likewise for multi-pair overloads.
@@ -1611,7 +1746,7 @@ final class ReactorRules {
   static final class StepVerifierFromMono<T> {
     @BeforeTemplate
     StepVerifier.FirstStep<? extends T> before(Mono<T> mono) {
-      return StepVerifier.create(mono);
+      return Refaster.anyOf(StepVerifier.create(mono), mono.flux().as(StepVerifier::create));
     }
 
     @AfterTemplate
@@ -1669,7 +1804,7 @@ final class ReactorRules {
   // a `@Matches(DoesNotDropElements.class)` or `@NotMatches(MayDropElements.class)` guard.
   static final class FluxAsStepVerifierExpectNext<T, L extends List<T>> {
     @BeforeTemplate
-    StepVerifier.Step<L> before(Flux<T> flux, Collector<? super T, ?, L> listCollector, T object) {
+    StepVerifier.Step<L> before(Flux<T> flux, T object, Collector<? super T, ?, L> listCollector) {
       return flux.collect(listCollector)
           .as(StepVerifier::create)
           .assertNext(list -> assertThat(list).containsExactly(object));
@@ -1784,4 +1919,76 @@ final class ReactorRules {
       return step.verifyTimeout(duration);
     }
   }
+
+  /**
+   * Prefer {@link Mono#fromFuture(Supplier)} over {@link Mono#fromFuture(CompletableFuture)}, as
+   * the former may defer initiation of the asynchronous computation until subscription.
+   */
+  static final class MonoFromFutureSupplier<T> {
+    // XXX: Constrain the `future` parameter using `@NotMatches(IsIdentityOperation.class)` once
+    // `IsIdentityOperation` no longer matches nullary method invocations.
+    @BeforeTemplate
+    Mono<T> before(CompletableFuture<T> future) {
+      return Mono.fromFuture(future);
+    }
+
+    @AfterTemplate
+    Mono<T> after(CompletableFuture<T> future) {
+      return Mono.fromFuture(() -> future);
+    }
+  }
+
+  /**
+   * Prefer {@link Mono#fromFuture(Supplier, boolean)} over {@link
+   * Mono#fromFuture(CompletableFuture, boolean)}, as the former may defer initiation of the
+   * asynchronous computation until subscription.
+   */
+  static final class MonoFromFutureSupplierBoolean<T> {
+    // XXX: Constrain the `future` parameter using `@NotMatches(IsIdentityOperation.class)` once
+    // `IsIdentityOperation` no longer matches nullary method invocations.
+    @BeforeTemplate
+    Mono<T> before(CompletableFuture<T> future, boolean suppressCancel) {
+      return Mono.fromFuture(future, suppressCancel);
+    }
+
+    @AfterTemplate
+    Mono<T> after(CompletableFuture<T> future, boolean suppressCancel) {
+      return Mono.fromFuture(() -> future, suppressCancel);
+    }
+  }
+
+  /**
+   * Don't propagate {@link Mono} cancellations to an upstream cache value computation, as
+   * completion of such computations may benefit concurrent or subsequent cache usages.
+   */
+  static final class MonoFromFutureAsyncLoadingCacheGet<K, V> {
+    @BeforeTemplate
+    Mono<V> before(AsyncLoadingCache<K, V> cache, K key) {
+      return Mono.fromFuture(() -> cache.get(key));
+    }
+
+    @AfterTemplate
+    Mono<V> after(AsyncLoadingCache<K, V> cache, K key) {
+      return Mono.fromFuture(() -> cache.get(key), /* suppressCancel= */ true);
+    }
+  }
+
+  /**
+   * Prefer {@link Flux#fromStream(Supplier)} over {@link Flux#fromStream(Stream)}, as the former
+   * yields a {@link Flux} that is more likely to behave as expected when subscribed to more than
+   * once.
+   */
+  static final class FluxFromStreamSupplier<T> {
+    // XXX: Constrain the `stream` parameter using `@NotMatches(IsIdentityOperation.class)` once
+    // `IsIdentityOperation` no longer matches nullary method invocations.
+    @BeforeTemplate
+    Flux<T> before(Stream<T> stream) {
+      return Flux.fromStream(stream);
+    }
+
+    @AfterTemplate
+    Flux<T> after(Stream<T> stream) {
+      return Flux.fromStream(() -> stream);
+    }
+  }
 }

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

@@ -4,6 +4,7 @@ import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
 import static java.util.Comparator.naturalOrder;
 import static java.util.Comparator.reverseOrder;
 import static java.util.function.Predicate.not;
+import static java.util.stream.Collectors.collectingAndThen;
 import static java.util.stream.Collectors.counting;
 import static java.util.stream.Collectors.filtering;
 import static java.util.stream.Collectors.flatMapping;
@@ -24,6 +25,7 @@ import com.google.common.collect.Streams;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
+import com.google.errorprone.refaster.annotation.AlsoNegation;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import com.google.errorprone.refaster.annotation.Matches;
 import com.google.errorprone.refaster.annotation.MayOptionallyUse;
@@ -37,6 +39,7 @@ import java.util.Comparator;
 import java.util.DoubleSummaryStatistics;
 import java.util.IntSummaryStatistics;
 import java.util.LongSummaryStatistics;
+import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.function.BinaryOperator;
@@ -254,32 +257,38 @@ final class StreamRules {
   // XXX: This rule assumes that any matched `Collector` does not perform any filtering.
   // (Perhaps we could add a `@Matches` guard that validates that the collector expression does not
   // contain a `Collectors#filtering` call. That'd still not be 100% accurate, though.)
-  static final class StreamIsEmpty<T> {
+  static final class StreamFindAnyIsEmpty<T, K, V, C extends Collection<K>, M extends Map<K, V>> {
     @BeforeTemplate
-    boolean before(Stream<T> stream, Collector<? super T, ?, ? extends Collection<?>> collector) {
+    boolean before(Stream<T> stream, Collector<? super T, ?, ? extends C> collector) {
       return Refaster.anyOf(
           stream.count() == 0,
           stream.count() <= 0,
           stream.count() < 1,
           stream.findFirst().isEmpty(),
-          stream.collect(collector).isEmpty());
+          stream.collect(collector).isEmpty(),
+          stream.collect(collectingAndThen(collector, C::isEmpty)));
+    }
+
+    @BeforeTemplate
+    boolean before2(Stream<T> stream, Collector<? super T, ?, ? extends M> collector) {
+      return stream.collect(collectingAndThen(collector, M::isEmpty));
     }
 
     @AfterTemplate
+    @AlsoNegation
     boolean after(Stream<T> stream) {
       return stream.findAny().isEmpty();
     }
   }
 
-  /** In order to test whether a stream has any element, simply try to find one. */
-  static final class StreamIsNotEmpty<T> {
+  /**
+   * Prefer {@link Stream#findAny()} over {@link Stream#findFirst()} if one only cares whether the
+   * stream is nonempty.
+   */
+  static final class StreamFindAnyIsPresent<T> {
     @BeforeTemplate
     boolean before(Stream<T> stream) {
-      return Refaster.anyOf(
-          stream.count() != 0,
-          stream.count() > 0,
-          stream.count() >= 1,
-          stream.findFirst().isPresent());
+      return stream.findFirst().isPresent();
     }
 
     @AfterTemplate