Merge remote-tracking branch 'origin/master' into website

See:
- https://github.com/raphw/byte-buddy/releases/tag/byte-buddy-1.14.19
- https://github.com/raphw/byte-buddy/compare/byte-buddy-1.14.18...byte-buddy-1.14.19

.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. `17.0.10`).
+- Error Prone version (e.g. `2.25.0`).
+- Error Prone Support version (e.g. `0.15.0`).
 
 ### 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

@@ -10,32 +10,43 @@ jobs:
     strategy:
       matrix:
         os: [ ubuntu-22.04 ]
-        jdk: [ 11.0.20, 17.0.8, 21.0.0 ]
+        jdk: [ 17.0.10, 21.0.2, 22.0.2 ]
         distribution: [ temurin ]
         experimental: [ false ]
         include:
           - os: macos-14
-            jdk: 17.0.8
+            jdk: 17.0.10
             distribution: temurin
             experimental: false
           - os: windows-2022
-            jdk: 17.0.8
+            jdk: 17.0.10
             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 and set up JDK and Maven
-        uses: s4u/setup-maven-action@fa2c7e4517ed008b1f73e7e0195a9eecf5582cd4 # v1.11.0
+        uses: s4u/setup-maven-action@489441643219d2b93ee2a127b2402eb640a1b947 # v1.13.0
         with:
           java-version: ${{ matrix.jdk }}
           java-distribution: ${{ matrix.distribution }}
-          maven-version: 3.9.6
+          maven-version: 3.9.8
       - name: Display build environment details
         run: mvn --version
       - name: Build project against vanilla Error Prone, compile Javadoc

.github/workflows/codeql.yml

@@ -21,20 +21,32 @@ jobs:
       security-events: write
     runs-on: ubuntu-22.04
     steps:
-      - name: Check out code and set up JDK and Maven
-        uses: s4u/setup-maven-action@fa2c7e4517ed008b1f73e7e0195a9eecf5582cd4 # v1.11.0
+      - name: Install Harden-Runner
+        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
         with:
-          java-version: 17.0.8
+          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: 17.0.10
           java-distribution: temurin
-          maven-version: 3.9.6
+          maven-version: 3.9.8
       - name: Initialize CodeQL
-        uses: github/codeql-action/init@b7bf0a3ed3ecfa44160715d7c442788f65f0f923 # v3.23.2
+        uses: github/codeql-action/init@c7f9125735019aa87cfc361530512d50ea439c71 # v3.25.1
         with:
           languages: ${{ matrix.language }}
       - name: Perform minimal build
         if: matrix.language == 'java'
         run: mvn -T1C clean package -DskipTests -Dverification.skip
       - name: Perform CodeQL analysis
-        uses: github/codeql-action/analyze@b7bf0a3ed3ecfa44160715d7c442788f65f0f923 # v3.23.2
+        uses: github/codeql-action/analyze@c7f9125735019aa87cfc361530512d50ea439c71 # v3.25.1
         with:
           category: /language:${{ matrix.language }}

.github/workflows/deploy-website.yml

@@ -11,26 +11,56 @@ jobs:
   build:
     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
-      - uses: ruby/setup-ruby@bd03e04863f52d169e18a2b190e8fa6b84938215 # v1.170.0
+          disable-sudo: true
+          egress-policy: block
+          allowed-endpoints: >
+            api.adoptium.net:443
+            api.github.com:443
+            bestpractices.coreinfrastructure.org:443
+            blog.picnic.nl:443
+            errorprone.info:443
+            github.com:443
+            img.shields.io:443
+            index.rubygems.org:443
+            jitpack.io:443
+            maven.apache.org:443
+            objects.githubusercontent.com:443
+            pitest.org:443
+            repo.maven.apache.org:443
+            rubygems.org:443
+            search.maven.org:443
+            securityscorecards.dev:443
+            sonarcloud.io:443
+            www.baeldung.com:443
+            www.bestpractices.dev:443
+            www.youtube.com:443
+            youtrack.jetbrains.com:443
+      - name: Check out code and set up JDK and Maven
+        uses: s4u/setup-maven-action@489441643219d2b93ee2a127b2402eb640a1b947 # v1.13.0
+        with:
+          java-version: 17.0.10
+          java-distribution: temurin
+          maven-version: 3.9.6
+      - 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: Compile project and extract data
+        run: mvn -T1C clean install -DskipTests -Dverification.skip -Pdocgen
       - name: Generate documentation
-        run: ./generate-docs.sh
+        run: mvn exec:java@generate-docs -pl documentation-support
       - name: Build website with Jekyll
         working-directory: ./website
         run: bundle exec jekyll build
       - name: Validate HTML output
         working-directory: ./website
-        # XXX: Drop `--disable_external true` once we fully adopted the
-        # "Refaster rules" terminology on our website and in the code.
-        run: bundle exec htmlproofer --disable_external true --check-external-hash false ./_site
+        # XXX: StackOverflow returns a 403 when run on GHA.
+        run: bundle exec htmlproofer --no-check-external-hash --swap-url 'https\://error-prone.picnic.tech:' --ignore-urls '/^https:\/\/stackoverflow.com\/.*/' ./_site
       - name: Upload website as artifact
         uses: actions/upload-pages-artifact@56afc609e74202658d3ffba0e8f6dda462b719fa # v3.0.1
         with:
@@ -46,6 +76,13 @@ 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@decdde0ac072f6dcbe43649d82d9c635fff5b4e4 # v4.0.4
+        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@b7bf0a3ed3ecfa44160715d7c442788f65f0f923 # v3.23.2
+        uses: github/codeql-action/upload-sarif@c7f9125735019aa87cfc361530512d50ea439c71 # v3.25.1
         with:
           sarif_file: results.sarif

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

@@ -11,13 +11,23 @@ jobs:
   analyze-pr:
     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
+            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@fa2c7e4517ed008b1f73e7e0195a9eecf5582cd4 # v1.11.0
+        uses: s4u/setup-maven-action@489441643219d2b93ee2a127b2402eb640a1b947 # v1.13.0
         with:
           checkout-fetch-depth: 2
-          java-version: 17.0.8
+          java-version: 17.0.10
           java-distribution: temurin
-          maven-version: 3.9.6
+          maven-version: 3.9.8
       - name: Run Pitest
         # By running with features `+GIT(from[HEAD~1]), +gitci`, Pitest only
         # analyzes lines changed in the associated pull request, as GitHub
@@ -28,7 +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@5d5d22a31266ced268874388b861e4b58bb5c2f3 # v4.3.1
+        uses: actions/upload-artifact@65462800fd760344b1a7b4382951275a0abb4808 # v4.3.3
         with:
           name: pitest-reports
           path: ./target/pit-reports-ci

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

@@ -19,14 +19,25 @@ jobs:
       pull-requests: write
     runs-on: ubuntu-22.04
     steps:
-      - name: Check out code and set up JDK and Maven
-        uses: s4u/setup-maven-action@fa2c7e4517ed008b1f73e7e0195a9eecf5582cd4 # v1.11.0
+      - name: Install Harden-Runner
+        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
         with:
-          java-version: 17.0.8
+          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: 17.0.10
           java-distribution: temurin
-          maven-version: 3.9.6
+          maven-version: 3.9.8
       - 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

@@ -18,20 +18,34 @@ jobs:
       github.event.issue.pull_request && contains(github.event.comment.body, '/integration-test')
     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
+            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@fa2c7e4517ed008b1f73e7e0195a9eecf5582cd4 # v1.11.0
+        uses: s4u/setup-maven-action@489441643219d2b93ee2a127b2402eb640a1b947 # v1.13.0
         with:
           checkout-ref: "refs/pull/${{ github.event.issue.number }}/head"
-          java-version: 17.0.8
+          java-version: 17.0.10
           java-distribution: temurin
-          maven-version: 3.9.6
+          maven-version: 3.9.8
       - name: Install project to local Maven repository
         run: mvn -T1C install -DskipTests -Dverification.skip
       - name: Run integration test
         run: xvfb-run ./integration-tests/checkstyle.sh "${{ runner.temp }}/artifacts"
       - name: Upload artifacts on failure
         if: ${{ failure() }}
-        uses: actions/upload-artifact@5d5d22a31266ced268874388b861e4b58bb5c2f3 # v4.3.1
+        uses: actions/upload-artifact@65462800fd760344b1a7b4382951275a0abb4808 # v4.3.3
         with:
           name: integration-test-checkstyle
           path: "${{ runner.temp }}/artifacts"

.github/workflows/sonarcloud.yml

@@ -13,18 +13,34 @@ 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.pull_request.head.repo.full_name == github.repository
+    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: Install Harden-Runner
+        uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
+        with:
+          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@fa2c7e4517ed008b1f73e7e0195a9eecf5582cd4 # v1.11.0
+        uses: s4u/setup-maven-action@489441643219d2b93ee2a127b2402eb640a1b947 # v1.13.0
         with:
           checkout-fetch-depth: 0
-          java-version: 17.0.8
+          java-version: 17.0.10
           java-distribution: temurin
-          maven-version: 3.9.6
+          maven-version: 3.9.8
       - 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>
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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)">
+                <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"
       ],

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
 
@@ -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

documentation-support/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.14.1-SNAPSHOT</version>
+        <version>0.18.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>documentation-support</artifactId>
@@ -37,10 +37,18 @@
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-annotations</artifactId>
         </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-core</artifactId>
+        </dependency>
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-databind</artifactId>
         </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.dataformat</groupId>
+            <artifactId>jackson-dataformat-yaml</artifactId>
+        </dependency>
         <dependency>
             <groupId>com.fasterxml.jackson.datatype</groupId>
             <artifactId>jackson-datatype-guava</artifactId>
@@ -67,6 +75,10 @@
             <groupId>com.google.guava</groupId>
             <artifactId>guava</artifactId>
         </dependency>
+        <dependency>
+            <groupId>io.github.java-diff-utils</groupId>
+            <artifactId>java-diff-utils</artifactId>
+        </dependency>
         <dependency>
             <groupId>org.assertj</groupId>
             <artifactId>assertj-core</artifactId>
@@ -95,4 +107,29 @@
             <scope>test</scope>
         </dependency>
     </dependencies>
+
+    <build>
+        <pluginManagement>
+            <plugins>
+                <plugin>
+                    <groupId>org.codehaus.mojo</groupId>
+                    <artifactId>exec-maven-plugin</artifactId>
+                    <executions>
+                        <execution>
+                            <id>generate-docs</id>
+                            <goals>
+                                <goal>java</goal>
+                            </goals>
+                            <configuration>
+                                <mainClass>tech.picnic.errorprone.documentation.JekyllCollectionGenerator</mainClass>
+                                <arguments>
+                                    <argument>${maven.multiModuleProjectDirectory}</argument>
+                                </arguments>
+                            </configuration>
+                        </execution>
+                    </executions>
+                </plugin>
+            </plugins>
+        </pluginManagement>
+    </build>
 </project>

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

@@ -135,8 +135,8 @@ 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();
     }
 
@@ -154,8 +154,8 @@ 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) {
+        extractIdentificationTestCases(methodInvocation, sink, state);
       }
     }
 
@@ -184,8 +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) {
+        extractReplacementTestCases(methodInvocation, sink, state);
       }
     }
 

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

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

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

@@ -0,0 +1,326 @@
+package tech.picnic.errorprone.documentation;
+
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.collect.ImmutableList.toImmutableList;
+import static com.google.common.collect.ImmutableListMultimap.flatteningToImmutableListMultimap;
+import static com.google.common.collect.ImmutableMap.toImmutableMap;
+import static com.google.common.collect.ImmutableTable.toImmutableTable;
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static java.nio.charset.StandardCharsets.UTF_8;
+import static java.util.Objects.requireNonNull;
+import static java.util.stream.Collectors.joining;
+
+import com.fasterxml.jackson.annotation.JsonAutoDetect.Visibility;
+import com.fasterxml.jackson.annotation.PropertyAccessor;
+import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.dataformat.yaml.YAMLGenerator;
+import com.fasterxml.jackson.dataformat.yaml.YAMLMapper;
+import com.github.difflib.DiffUtils;
+import com.github.difflib.UnifiedDiffUtils;
+import com.github.difflib.patch.Patch;
+import com.google.auto.value.AutoValue;
+import com.google.common.base.Function;
+import com.google.common.base.Splitter;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableListMultimap;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableTable;
+import com.google.common.collect.Sets;
+import com.google.errorprone.BugPattern.SeverityLevel;
+import java.io.BufferedWriter;
+import java.io.IOException;
+import java.nio.file.FileSystems;
+import java.nio.file.FileVisitResult;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.PathMatcher;
+import java.nio.file.Paths;
+import java.nio.file.SimpleFileVisitor;
+import java.nio.file.attribute.BasicFileAttributes;
+import java.util.ArrayList;
+import java.util.List;
+import org.jspecify.annotations.Nullable;
+import tech.picnic.errorprone.documentation.BugPatternExtractor.BugPatternDocumentation;
+import tech.picnic.errorprone.documentation.BugPatternTestExtractor.IdentificationTestEntry;
+import tech.picnic.errorprone.documentation.BugPatternTestExtractor.ReplacementTestEntry;
+import tech.picnic.errorprone.documentation.BugPatternTestExtractor.TestCase;
+import tech.picnic.errorprone.documentation.BugPatternTestExtractor.TestCases;
+import tech.picnic.errorprone.documentation.BugPatternTestExtractor.TestEntry;
+import tech.picnic.errorprone.documentation.models.RefasterTemplateCollectionTestData;
+import tech.picnic.errorprone.documentation.models.RefasterTemplateTestData;
+
+// XXX: Rename this class. Then also update the reference in `website/.gitignore`.
+// XXX: Now that we have bug checkers in multiple Maven modules, we should
+// likely document the source of each check on the website, perhaps even
+// grouping them by module.
+public final class JekyllCollectionGenerator {
+  // XXX: Find a bette name. Also, externalize this.
+  private static final PathMatcher PATH_MATCHER =
+      FileSystems.getDefault().getPathMatcher("glob:**/target/docs/*.json");
+
+  // XXX: Review class setup.
+  private JekyllCollectionGenerator() {}
+
+  public static void main(String[] args) throws IOException {
+    checkArgument(args.length == 1, "Precisely one project root path must be provided");
+    Path projectRoot = Paths.get(args[0]).toAbsolutePath();
+
+    generateIndex(projectRoot);
+    PageGenerator.apply(projectRoot);
+  }
+
+  private static void generateIndex(Path projectRoot) throws IOException {
+    try (BufferedWriter writer =
+        Files.newBufferedWriter(projectRoot.resolve("website").resolve("index.md"), UTF_8)) {
+      writer.write("---");
+      writer.newLine();
+      writer.write("layout: default");
+      writer.newLine();
+      writer.write("title: Home");
+      writer.newLine();
+      writer.write("nav_order: 1");
+      writer.newLine();
+      writer.write("---");
+      writer.newLine();
+      writer.write(
+          Files.readString(projectRoot.resolve("README.md")).replace("=\"website/", "=\""));
+    }
+  }
+
+  // XXX: Review this class should be split in two: one for bug patterns and one for Refaster rules.
+  private static final class PageGenerator extends SimpleFileVisitor<Path> {
+    private static final Splitter LINE_SPLITTER = Splitter.on(System.lineSeparator());
+    private static final YAMLMapper YAML_MAPPER =
+        YAMLMapper.builder()
+            .visibility(PropertyAccessor.FIELD, Visibility.ANY)
+            .disable(JsonGenerator.Feature.AUTO_CLOSE_TARGET)
+            .enable(YAMLGenerator.Feature.MINIMIZE_QUOTES)
+            .enable(YAMLGenerator.Feature.USE_PLATFORM_LINE_BREAKS)
+            .build();
+
+    // XXX: Rename the data types?
+    private final List<BugPatternDocumentation> bugPatterns = new ArrayList<>();
+    private final List<TestCases> bugPatternTests = new ArrayList<>();
+    private final List<RefasterTemplateCollectionTestData> refasterTemplateCollectionTests =
+        new ArrayList<>();
+
+    static void apply(Path projectRoot) throws IOException {
+      PageGenerator pageGenerator = new PageGenerator();
+      Files.walkFileTree(projectRoot, pageGenerator);
+      pageGenerator.writePages(projectRoot);
+    }
+
+    @Override
+    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
+      if (!PATH_MATCHER.matches(file)) {
+        return FileVisitResult.CONTINUE;
+      }
+
+      // XXX: If we use a consistent ID separator, then this can become a switch statement. Now we
+      // depend on evaluation order.
+      // XXX: Alternatively, use polymorphism and let Jackson figure it out.
+      String fileName = file.getFileName().toString();
+      if (fileName.startsWith("bugpattern-test")) {
+        bugPatternTests.add(Json.read(file, TestCases.class));
+      } else if (fileName.startsWith("bugpattern")) {
+        bugPatterns.add(Json.read(file, BugPatternDocumentation.class));
+      } else if (fileName.startsWith("refaster-test")) {
+        refasterTemplateCollectionTests.add(
+            Json.read(file, RefasterTemplateCollectionTestData.class));
+      } else {
+        // XXX: Handle differently?
+        throw new IllegalStateException("Unexpected file: " + fileName);
+      }
+
+      return FileVisitResult.CONTINUE;
+    }
+
+    private void writePages(Path projectRoot) throws IOException {
+      Path website = projectRoot.resolve("website");
+      writePages(
+          website.resolve("_bugpatterns"),
+          getJekyllBugPatternDescriptions(projectRoot),
+          JekyllBugPatternDescription::name);
+      writePages(
+          website.resolve("_refasterrules"),
+          getJekyllRefasterRuleCollectionDescription(),
+          JekyllRefasterRuleCollectionDescription::name);
+    }
+
+    private static <T> void writePages(
+        Path directory, ImmutableList<T> documents, Function<T, String> nameExtractor)
+        throws IOException {
+      for (T document : documents) {
+        Files.createDirectories(directory);
+        try (BufferedWriter writer =
+            Files.newBufferedWriter(
+                directory.resolve(nameExtractor.apply(document) + ".md"), UTF_8)) {
+          YAML_MAPPER.writeValue(writer, document);
+          writer.write("---");
+          writer.newLine();
+        }
+      }
+    }
+
+    private ImmutableList<JekyllBugPatternDescription> getJekyllBugPatternDescriptions(
+        Path projectRoot) {
+      ImmutableListMultimap<String, TestEntry> bugPatternTestCases =
+          bugPatternTests.stream()
+              .flatMap(testCases -> testCases.testCases().stream())
+              .collect(
+                  flatteningToImmutableListMultimap(
+                      TestCase::classUnderTest, t -> t.entries().stream()));
+
+      return bugPatterns.stream()
+          .map(
+              b ->
+                  new AutoValue_JekyllCollectionGenerator_JekyllBugPatternDescription(
+                      b.name(),
+                      b.name(),
+                      b.summary(),
+                      b.severityLevel(),
+                      b.tags(),
+                      // XXX: Derive `Path` from filesytem.
+                      Path.of(b.source()).relativize(projectRoot).toString(),
+                      bugPatternTestCases.get(b.fullyQualifiedName()).stream()
+                          .filter(t -> t.type() == TestEntry.TestType.IDENTIFICATION)
+                          .map(t -> ((IdentificationTestEntry) t).code())
+                          .collect(toImmutableList()),
+                      bugPatternTestCases.get(b.fullyQualifiedName()).stream()
+                          .filter(t -> t.type() == TestEntry.TestType.REPLACEMENT)
+                          .map(t -> generateDiff((ReplacementTestEntry) t))
+                          .collect(toImmutableList())))
+          .collect(toImmutableList());
+    }
+
+    private ImmutableList<JekyllRefasterRuleCollectionDescription>
+        getJekyllRefasterRuleCollectionDescription() {
+      ImmutableTable<String, Boolean, List<RefasterTemplateTestData>> refasterTests =
+          refasterTemplateCollectionTests.stream()
+              .collect(
+                  toImmutableTable(
+                      RefasterTemplateCollectionTestData::templateCollection,
+                      RefasterTemplateCollectionTestData::isInput,
+                      RefasterTemplateCollectionTestData::templateTests));
+
+      return refasterTests.rowMap().entrySet().stream()
+          .map(
+              c ->
+                  new AutoValue_JekyllCollectionGenerator_JekyllRefasterRuleCollectionDescription(
+                      c.getKey(),
+                      c.getKey(),
+                      // XXX: Derive severity from input.
+                      SUGGESTION,
+                      // XXX: Derive tags from input (or drop this feature).
+                      ImmutableList.of("Simplification"),
+                      // XXX: Derive source location from input.
+                      String.format(
+                          "error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/%s.java",
+                          c.getKey()),
+                      getRules(c.getValue().get(true), c.getValue().get(false))))
+          .collect(toImmutableList());
+    }
+
+    private static ImmutableList<JekyllRefasterRuleCollectionDescription.Rule> getRules(
+        @Nullable List<RefasterTemplateTestData> inputTests,
+        @Nullable List<RefasterTemplateTestData> outputTests) {
+      ImmutableMap<String, String> inputs = indexRefasterTestData(inputTests);
+      ImmutableMap<String, String> outputs = indexRefasterTestData(outputTests);
+
+      return Sets.intersection(inputs.keySet(), outputs.keySet()).stream()
+          .map(
+              name ->
+                  new AutoValue_JekyllCollectionGenerator_JekyllRefasterRuleCollectionDescription_Rule(
+                      name,
+                      // XXX: Derive severity from input.
+                      SUGGESTION,
+                      // XXX: Derive tags from input (or drop this feature).
+                      ImmutableList.of("Simplification"),
+                      generateDiff(
+                          requireNonNull(inputs.get(name), "Input"),
+                          requireNonNull(outputs.get(name), "Output"))))
+          .collect(toImmutableList());
+    }
+
+    private static ImmutableMap<String, String> indexRefasterTestData(
+        @Nullable List<RefasterTemplateTestData> data) {
+      return data == null
+          ? ImmutableMap.of()
+          : data.stream()
+              .collect(
+                  toImmutableMap(
+                      RefasterTemplateTestData::templateName,
+                      RefasterTemplateTestData::templateTestContent));
+    }
+
+    private static String generateDiff(ReplacementTestEntry testEntry) {
+      return generateDiff(testEntry.input(), testEntry.output());
+    }
+
+    private static String generateDiff(String before, String after) {
+      // XXX: Extract splitter.
+      List<String> originalLines = LINE_SPLITTER.splitToList(before);
+      List<String> replacementLines = LINE_SPLITTER.splitToList(after);
+
+      Patch<String> diff = DiffUtils.diff(originalLines, replacementLines);
+
+      return UnifiedDiffUtils.generateUnifiedDiff(
+              "", "", originalLines, diff, Integer.MAX_VALUE / 2)
+          .stream()
+          .skip(3)
+          .collect(joining(System.lineSeparator()));
+    }
+  }
+
+  @AutoValue
+  abstract static class JekyllBugPatternDescription {
+    // XXX: Make this a derived property?
+    abstract String title();
+
+    abstract String name();
+
+    abstract String summary();
+
+    abstract SeverityLevel severity();
+
+    abstract ImmutableList<String> tags();
+
+    // XXX: The documentation could link to the original test code. Perhaps even with the correct
+    // line numbers.
+    abstract String source();
+
+    // XXX: The `identification` and `replacement` fields have odd names.
+    abstract ImmutableList<String> identification();
+
+    abstract ImmutableList<String> replacement();
+  }
+
+  @AutoValue
+  abstract static class JekyllRefasterRuleCollectionDescription {
+    // XXX: Make this a derived property?
+    abstract String title();
+
+    abstract String name();
+
+    abstract SeverityLevel severity();
+
+    abstract ImmutableList<String> tags();
+
+    // XXX: The documentation could link to the original test code. Perhaps even with the correct
+    // line numbers. If we do this, we should do the same for individual rules.
+    abstract String source();
+
+    abstract ImmutableList<Rule> rules();
+
+    @AutoValue
+    abstract static class Rule {
+      abstract String name();
+
+      abstract SeverityLevel severity();
+
+      abstract ImmutableList<String> tags();
+
+      abstract String diff();
+    }
+  }
+}

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

@@ -0,0 +1,70 @@
+package tech.picnic.errorprone.documentation;
+
+import static com.google.common.collect.ImmutableList.toImmutableList;
+
+import com.google.auto.service.AutoService;
+import com.google.common.collect.ImmutableList;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.annotations.Immutable;
+import com.sun.source.tree.ClassTree;
+import com.sun.source.tree.MethodTree;
+import java.util.Optional;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import tech.picnic.errorprone.documentation.models.RefasterTemplateCollectionTestData;
+import tech.picnic.errorprone.documentation.models.RefasterTemplateTestData;
+
+@Immutable
+@AutoService(Extractor.class)
+@SuppressWarnings("rawtypes" /* See https://github.com/google/auto/issues/870. */)
+public final class RefasterTestInputExtractor
+    implements Extractor<RefasterTemplateCollectionTestData> {
+  private static final Pattern TEST_CLASS_NAME_PATTERN = Pattern.compile("(.*)Test");
+
+  @Override
+  public String identifier() {
+    return "refaster-test-input";
+  }
+
+  @Override
+  public Optional<RefasterTemplateCollectionTestData> tryExtract(
+      ClassTree tree, VisitorState state) {
+    // XXX: The `String.valueOf` call is a hack to avoid an NPE in the absence of an explicit
+    // package declaration.
+    if (!String.valueOf(state.getPath().getCompilationUnit().getPackageName()).contains("input")) {
+      return Optional.empty();
+    }
+
+    Optional<String> className = getClassUnderTest(tree);
+    if (className.isEmpty()) {
+      return Optional.empty();
+    }
+
+    ImmutableList<RefasterTemplateTestData> templateTests =
+        tree.getMembers().stream()
+            .filter(MethodTree.class::isInstance)
+            .map(MethodTree.class::cast)
+            .filter(m -> m.getName().toString().startsWith("test"))
+            .map(
+                m ->
+                    RefasterTemplateTestData.create(
+                        m.getName().toString().replace("test", ""), getSourceCode(m, state)))
+            .collect(toImmutableList());
+
+    return Optional.of(
+        RefasterTemplateCollectionTestData.create(
+            className.orElseThrow(), /* isInput= */ true, templateTests));
+  }
+
+  private static Optional<String> getClassUnderTest(ClassTree tree) {
+    return Optional.of(TEST_CLASS_NAME_PATTERN.matcher(tree.getSimpleName().toString()))
+        .filter(Matcher::matches)
+        .map(m -> m.group(1));
+  }
+
+  // XXX: Duplicated from `SourceCode`. Can we do better?
+  private static String getSourceCode(MethodTree tree, VisitorState state) {
+    String src = state.getSourceForNode(tree);
+    return src != null ? src : tree.toString();
+  }
+}

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

@@ -0,0 +1,70 @@
+package tech.picnic.errorprone.documentation;
+
+import static com.google.common.collect.ImmutableList.toImmutableList;
+
+import com.google.auto.service.AutoService;
+import com.google.common.collect.ImmutableList;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.annotations.Immutable;
+import com.sun.source.tree.ClassTree;
+import com.sun.source.tree.MethodTree;
+import java.util.Optional;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import tech.picnic.errorprone.documentation.models.RefasterTemplateCollectionTestData;
+import tech.picnic.errorprone.documentation.models.RefasterTemplateTestData;
+
+@Immutable
+@AutoService(Extractor.class)
+@SuppressWarnings("rawtypes" /* See https://github.com/google/auto/issues/870. */)
+public final class RefasterTestOutputExtractor
+    implements Extractor<RefasterTemplateCollectionTestData> {
+  private static final Pattern TEST_CLASS_NAME_PATTERN = Pattern.compile("(.*)Test");
+
+  @Override
+  public String identifier() {
+    return "refaster-test-output";
+  }
+
+  @Override
+  public Optional<RefasterTemplateCollectionTestData> tryExtract(
+      ClassTree tree, VisitorState state) {
+    // XXX: The `String.valueOf` call is a hack to avoid an NPE in the absence of an explicit
+    // package declaration.
+    if (!String.valueOf(state.getPath().getCompilationUnit().getPackageName()).contains("output")) {
+      return Optional.empty();
+    }
+
+    Optional<String> className = getClassUnderTest(tree);
+    if (className.isEmpty()) {
+      return Optional.empty();
+    }
+
+    ImmutableList<RefasterTemplateTestData> templateTests =
+        tree.getMembers().stream()
+            .filter(MethodTree.class::isInstance)
+            .map(MethodTree.class::cast)
+            .filter(m -> m.getName().toString().startsWith("test"))
+            .map(
+                m ->
+                    RefasterTemplateTestData.create(
+                        m.getName().toString().replace("test", ""), getSourceCode(m, state)))
+            .collect(toImmutableList());
+
+    return Optional.of(
+        RefasterTemplateCollectionTestData.create(
+            className.orElseThrow(), /* isInput= */ false, templateTests));
+  }
+
+  private static Optional<String> getClassUnderTest(ClassTree tree) {
+    return Optional.of(TEST_CLASS_NAME_PATTERN.matcher(tree.getSimpleName().toString()))
+        .filter(Matcher::matches)
+        .map(m -> m.group(1));
+  }
+
+  // XXX: Duplicated from `SourceCode`. Can we do better?
+  private static String getSourceCode(MethodTree tree, VisitorState state) {
+    String src = state.getSourceForNode(tree);
+    return src != null ? src : tree.toString();
+  }
+}

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

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

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

@@ -0,0 +1,27 @@
+package tech.picnic.errorprone.documentation.models;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+import com.google.auto.value.AutoValue;
+import com.google.common.collect.ImmutableList;
+
+// XXX: Make properties package-private if type is moved to shared package.
+@AutoValue
+@JsonDeserialize(as = AutoValue_RefasterTemplateCollectionTestData.class)
+public abstract class RefasterTemplateCollectionTestData {
+  public static RefasterTemplateCollectionTestData create(
+      String templateCollection,
+      boolean isInput,
+      ImmutableList<RefasterTemplateTestData> templatesTests) {
+    return new AutoValue_RefasterTemplateCollectionTestData(
+        templateCollection, isInput, templatesTests);
+  }
+
+  public abstract String templateCollection();
+
+  // XXX: This annotation prevents serialization of fields `isInput` *and* `input`. Review.
+  @JsonProperty("isInput")
+  public abstract boolean isInput();
+
+  public abstract ImmutableList<RefasterTemplateTestData> templateTests();
+}

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

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

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

@@ -0,0 +1,17 @@
+package tech.picnic.errorprone.documentation.models;
+
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+import com.google.auto.value.AutoValue;
+
+// XXX: Make properties package-private if type is moved to shared package.
+@AutoValue
+@JsonDeserialize(as = AutoValue_RefasterTemplateTestData.class)
+public abstract class RefasterTemplateTestData {
+  public static RefasterTemplateTestData create(String templateName, String templateTestContent) {
+    return new AutoValue_RefasterTemplateTestData(templateName, templateTestContent);
+  }
+
+  public abstract String templateName();
+
+  public abstract String templateTestContent();
+}

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

@@ -93,13 +93,20 @@ final class DocumentationGeneratorTaskListenerTest {
         "DocumentationGeneratorTaskListenerTestClass.java",
         "class DocumentationGeneratorTaskListenerTestClass {}");
 
-    // XXX: Once we support only JDK 15+, use a text block for the `expected` string.
     assertThat(
             outputDirectory.resolve(
                 "documentation-generator-task-listener-test-DocumentationGeneratorTaskListenerTestClass.json"))
         .content(UTF_8)
         .isEqualToIgnoringWhitespace(
-            "{\"className\":\"DocumentationGeneratorTaskListenerTestClass\",\"path\":[\"CLASS: DocumentationGeneratorTaskListenerTestClass\",\"COMPILATION_UNIT\"]}");
+            """
+            {
+              "className": "DocumentationGeneratorTaskListenerTestClass",
+              "path": [
+                "CLASS: DocumentationGeneratorTaskListenerTestClass",
+                "COMPILATION_UNIT"
+              ]
+            }
+            """);
   }
 
   @Immutable
@@ -125,8 +132,8 @@ final class DocumentationGeneratorTaskListenerTest {
     }
 
     private static String describeTree(Tree tree) {
-      return (tree instanceof ClassTree)
-          ? String.join(": ", String.valueOf(tree.getKind()), ((ClassTree) tree).getSimpleName())
+      return (tree instanceof ClassTree clazz)
+          ? String.join(": ", String.valueOf(tree.getKind()), clazz.getSimpleName())
           : tree.getKind().toString();
     }
   }

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

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

error-prone-contrib/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.14.1-SNAPSHOT</version>
+        <version>0.18.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>error-prone-contrib</artifactId>
@@ -122,6 +122,11 @@
             <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>
@@ -279,7 +284,6 @@
                             </path>
                         </annotationProcessorPaths>
                         <compilerArgs combine.children="append">
-                            <arg>-Xplugin:RefasterRuleCompiler</arg>
                             <arg>-Xplugin:DocumentationGenerator -XoutputDirectory=${project.build.directory}/docs</arg>
                         </compilerArgs>
                     </configuration>
@@ -287,4 +291,34 @@
             </plugins>
         </pluginManagement>
     </build>
+
+    <!-- XXX: Drop this hack; then also drop any references to `docgen`. -->
+    <profiles>
+        <profile>
+            <id>docgen</id>
+            <build>
+                <plugins>
+                    <plugin>
+                        <groupId>org.codehaus.mojo</groupId>
+                        <artifactId>build-helper-maven-plugin</artifactId>
+                        <version>3.3.0</version>
+                        <executions>
+                            <execution>
+                                <id>add-test-source</id>
+                                <goals>
+                                    <goal>add-test-source</goal>
+                                </goals>
+                                <phase>generate-test-sources</phase>
+                                <configuration>
+                                    <sources>
+                                        <source>src/test/resources</source>
+                                    </sources>
+                                </configuration>
+                            </execution>
+                        </executions>
+                    </plugin>
+                </plugins>
+            </build>
+        </profile>
+    </profiles>
 </project>

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

@@ -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/CanonicalAnnotationSyntax.java

@@ -19,7 +19,6 @@ import com.sun.source.tree.AnnotationTree;
 import com.sun.source.tree.AssignmentTree;
 import com.sun.source.tree.ExpressionTree;
 import com.sun.source.tree.NewArrayTree;
-import com.sun.source.tree.Tree.Kind;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
@@ -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

@@ -81,9 +81,8 @@ public final class CanonicalClassNameUsage extends BugChecker
       path = path.getParentPath();
     }
 
-    return path.getLeaf() instanceof MethodInvocationTree
-        && isOwnedByCanonicalNameUsingType(
-            ASTHelpers.getSymbol((MethodInvocationTree) path.getLeaf()));
+    return path.getLeaf() instanceof MethodInvocationTree methodInvocation
+        && isOwnedByCanonicalNameUsingType(ASTHelpers.getSymbol(methodInvocation));
   }
 
   private static boolean isOwnedByCanonicalNameUsingType(MethodSymbol symbol) {

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

@@ -101,19 +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())
@@ -151,11 +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/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/FluxFlatMapUsage.java

@@ -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,

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

@@ -245,8 +245,8 @@ 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

@@ -51,6 +51,7 @@ import tech.picnic.errorprone.utils.SourceCode;
 // is effectively the identity operation.
 // XXX: Also flag nullary instance method invocations that represent an identity conversion, such as
 // `Boolean#booleanValue()`, `Byte#byteValue()` and friends.
+// XXX: Also flag redundant round-trip conversions such as `path.toFile().toPath()`.
 @AutoService(BugChecker.class)
 @BugPattern(
     summary = "Avoid or clarify identity conversions",
@@ -124,8 +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

@@ -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

@@ -16,7 +16,6 @@ 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.utils.SourceCode;
 
@@ -41,12 +40,12 @@ 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/JUnitValueSource.java

@@ -232,7 +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
@@ -265,8 +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(", ")))
@@ -276,16 +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) {
@@ -297,11 +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

@@ -31,7 +31,6 @@ 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;
@@ -52,6 +51,9 @@ import tech.picnic.errorprone.utils.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 +67,15 @@ 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 +125,9 @@ 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(
@@ -193,24 +192,24 @@ 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);
 

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

@@ -36,6 +36,10 @@ import tech.picnic.errorprone.utils.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

@@ -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/MongoDBTextFilterUsage.java

@@ -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/NestedPublishers.java

@@ -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/NonStaticImport.java

@@ -169,10 +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,
@@ -211,7 +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/OptionalOrElse.java

@@ -0,0 +1,135 @@
+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.google.errorprone.util.ASTHelpers;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.IdentifierTree;
+import com.sun.source.tree.LiteralTree;
+import com.sun.source.tree.MemberSelectTree;
+import com.sun.source.tree.MethodInvocationTree;
+import java.util.Optional;
+import java.util.function.Supplier;
+import tech.picnic.errorprone.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: Consider also implementing the inverse, in which `.orElseGet(() -> someConstant)` is
+// flagged.
+// XXX: Once the `MethodReferenceUsageCheck` becomes generally usable, consider leaving the method
+// reference cleanup to that check, and express the remainder of the logic in this class using a
+// Refaster template, i.c.w. a `@Matches` constraint that implements the `requiresComputation`
+// logic.
+@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 OptionalOrElse extends BugChecker implements MethodInvocationTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Matcher<ExpressionTree> OPTIONAL_OR_ELSE_METHOD =
+      instanceMethod().onExactClass(Optional.class.getCanonicalName()).namedAnyOf("orElse");
+  // XXX: Also exclude invocations of `@Placeholder`-annotated methods.
+  private static final Matcher<ExpressionTree> REFASTER_METHOD =
+      staticMethod().onClass(Refaster.class.getCanonicalName());
+
+  /** Instantiates a new {@link OptionalOrElse} instance. */
+  public OptionalOrElse() {}
+
+  @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 (!requiresComputation(argument) || 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);
+  }
+
+  /**
+   * Tells whether the given expression contains anything other than a literal or a (possibly
+   * dereferenced) variable or constant.
+   */
+  private static boolean requiresComputation(ExpressionTree tree) {
+    return !(tree instanceof IdentifierTree
+        || tree instanceof LiteralTree
+        || (tree instanceof MemberSelectTree memberSelect
+            && !requiresComputation(memberSelect.getExpression()))
+        || ASTHelpers.constValue(tree) != null);
+  }
+
+  /** Returns the nullary method reference matching the given expression, if any. */
+  private static Optional<String> tryMethodReferenceConversion(
+      ExpressionTree tree, VisitorState state) {
+    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 (requiresComputation(memberSelect.getExpression())) {
+      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

@@ -22,6 +22,7 @@ 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;
@@ -44,8 +45,9 @@ import tech.picnic.errorprone.utils.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,
@@ -147,38 +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:
-        SuggestedFix.Builder fix = SuggestedFix.builder();
-        String replacement =
-            SuggestedFixes.qualifyStaticImport(
-                Comparator.class.getCanonicalName() + '.' + preferredMethodName, fix, state);
-        return fix.replace(expr, replacement).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

@@ -331,36 +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)));
   }
 

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

@@ -105,9 +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

@@ -34,7 +34,9 @@ import tech.picnic.errorprone.utils.Flags;
 @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,

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

@@ -1,6 +1,5 @@
 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;
@@ -25,7 +24,6 @@ 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.utils.AnnotationAttributeMatcher;
 import tech.picnic.errorprone.utils.SourceCode;
@@ -80,31 +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(

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

@@ -39,11 +39,13 @@ 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;
@@ -100,6 +102,7 @@ public final class StaticImport extends BugChecker implements MemberSelectTreeMa
           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",
@@ -209,15 +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/TimeZoneUsage.java

@@ -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,

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 +72,39 @@ final class ClassRules {
       return clazz::isInstance;
     }
   }
+
+  /**
+   * Prefer {@link Class#cast(Object)} method references over lambda expressions that require naming
+   * a variable.
+   */
+  // XXX: Once the `ClassReferenceCast` rule is dropped, rename this rule to just `ClassCast`.
+  static final class ClassLiteralCast<T, S> {
+    @BeforeTemplate
+    @SuppressWarnings("unchecked")
+    Function<T, S> before() {
+      return t -> (S) t;
+    }
+
+    @AfterTemplate
+    Function<T, S> after() {
+      return Refaster.<S>clazz()::cast;
+    }
+  }
+
+  /**
+   * 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
@@ -337,7 +383,9 @@ final class CollectionRules {
 
   /**
    * 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

@@ -16,11 +16,15 @@ 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.Optional;
@@ -92,6 +96,24 @@ 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
@@ -226,14 +248,46 @@ final class ComparatorRules {
    * 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 MinOfCollection<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);
     }
   }
@@ -269,7 +323,7 @@ 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,
@@ -284,7 +338,7 @@ 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.min(value1, value2, cmp);
     }
   }
@@ -293,14 +347,46 @@ final class ComparatorRules {
    * 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 MaxOfCollection<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);
     }
   }
@@ -336,7 +422,7 @@ 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,
@@ -351,7 +437,7 @@ 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);
     }
   }
@@ -419,4 +505,34 @@ final class ComparatorRules {
       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.

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/InputStreamRules.java

@@ -9,8 +9,6 @@ import java.io.OutputStream;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 
 /** Refaster rules related to expressions dealing with {@link InputStream}s. */
-// XXX: Add a rule for `ByteStreams.skipFully(in, n)` -> `in.skipNBytes(n)` once we have a way to
-// target JDK 12+ APIs.
 @OnlineDocumentation
 final class InputStreamRules {
   private InputStreamRules() {}
@@ -38,4 +36,28 @@ final class InputStreamRules {
       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

@@ -26,6 +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.
@@ -40,19 +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() {}
 
-  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();
     }
   }
 
@@ -62,12 +327,7 @@ final class JUnitToAssertJRules {
       return Assertions.fail(message);
     }
 
-    // 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.
+    // XXX: Add `@UseImportPolicy(STATIC_IMPORT_ALWAYS)`. See `Fail` comment.
     @AfterTemplate
     T after(String message) {
       return fail(message);
@@ -80,28 +340,24 @@ final class JUnitToAssertJRules {
       return Assertions.fail(message, throwable);
     }
 
-    // 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.
+    // XXX: Add `@UseImportPolicy(STATIC_IMPORT_ALWAYS)`. See `Fail` comment.
     @AfterTemplate
     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);
     }
   }
 

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

@@ -27,6 +27,19 @@ import tech.picnic.errorprone.refaster.matchers.IsLikelyTrivialComputation;
 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.
@@ -360,7 +373,7 @@ 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("NestedOptionals")
     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.
@@ -386,9 +399,13 @@ 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),
@@ -442,9 +459,7 @@ 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/ReactorRules.java

@@ -3,7 +3,6 @@ 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;
@@ -34,6 +33,7 @@ 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;
@@ -41,6 +41,7 @@ import java.util.function.Function;
 import java.util.function.Predicate;
 import java.util.function.Supplier;
 import java.util.stream.Collector;
+import java.util.stream.Stream;
 import org.jspecify.annotations.Nullable;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
@@ -52,7 +53,6 @@ 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;
@@ -380,30 +380,23 @@ 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);
     }
   }
 
@@ -489,15 +482,20 @@ 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);
     }
   }
 
@@ -566,6 +564,7 @@ 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));
@@ -1205,6 +1204,26 @@ 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.
@@ -1899,4 +1918,60 @@ 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);
+    }
+  }
+
+  /**
+   * 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

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

@@ -29,7 +29,9 @@ final class StringRules {
   private StringRules() {}
 
   /** Prefer {@link String#isEmpty()} over alternatives that consult the string's length. */
-  // XXX: Once we target JDK 15+, generalize this rule to cover all `CharSequence` subtypes.
+  // XXX: Now that we build with JDK 15+, this rule can be generalized to cover all `CharSequence`
+  // subtypes. This does require a mechanism (perhaps an annotation, or a separate Maven module) to
+  // make sure that non-String expressions are rewritten only if client code also targets JDK 15+.
   static final class StringIsEmpty {
     @BeforeTemplate
     boolean before(String str) {
@@ -44,7 +46,9 @@ final class StringRules {
   }
 
   /** Prefer a method reference to {@link String#isEmpty()} over the equivalent lambda function. */
-  // XXX: Once we target JDK 15+, generalize this rule to cover all `CharSequence` subtypes.
+  // XXX: Now that we build with JDK 15+, this rule can be generalized to cover all `CharSequence`
+  // subtypes. However, `CharSequence::isEmpty` isn't as nice as `String::isEmpty`, so we might want
+  // to introduce a rule that suggests `String::isEmpty` where possible.
   // 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.
   static final class StringIsEmptyPredicate {
@@ -60,7 +64,9 @@ final class StringRules {
   }
 
   /** Prefer a method reference to {@link String#isEmpty()} over the equivalent lambda function. */
-  // XXX: Once we target JDK 15+, generalize this rule to cover all `CharSequence` subtypes.
+  // XXX: Now that we build with JDK 15+, this rule can be generalized to cover all `CharSequence`
+  // subtypes. However, `CharSequence::isEmpty` isn't as nice as `String::isEmpty`, so we might want
+  // to introduce a rule that suggests `String::isEmpty` where possible.
   static final class StringIsNotEmptyPredicate {
     @BeforeTemplate
     Predicate<String> before() {
@@ -162,6 +168,39 @@ final class StringRules {
     }
   }
 
+  /**
+   * Prefer direct invocation of {@link String#String(char[], int, int)} over the indirection
+   * introduced by alternatives.
+   */
+  static final class NewStringFromCharArraySubSequence {
+    @BeforeTemplate
+    String before(char[] data, int offset, int count) {
+      return Refaster.anyOf(
+          String.valueOf(data, offset, count), String.copyValueOf(data, offset, count));
+    }
+
+    @AfterTemplate
+    String after(char[] data, int offset, int count) {
+      return new String(data, offset, count);
+    }
+  }
+
+  /**
+   * Prefer direct invocation of {@link String#String(char[])} over the indirection introduced by
+   * alternatives.
+   */
+  static final class NewStringFromCharArray {
+    @BeforeTemplate
+    String before(char[] data) {
+      return Refaster.anyOf(String.valueOf(data), new String(data, 0, data.length));
+    }
+
+    @AfterTemplate
+    String after(char[] data) {
+      return new String(data);
+    }
+  }
+
   /**
    * Prefer direct delegation to {@link String#valueOf(Object)} over the indirection introduced by
    * {@link Objects#toString(Object)}.

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

@@ -29,6 +29,7 @@ import org.assertj.core.api.ThrowableAssert.ThrowingCallable;
 import org.testng.Assert;
 import org.testng.Assert.ThrowingRunnable;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
+import tech.picnic.errorprone.refaster.annotation.TypeMigration;
 
 /**
  * Refaster rules that replace TestNG assertions with equivalent AssertJ assertions.
@@ -48,32 +49,107 @@ import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
  * List<Map<String, Object>> myMaps = new ArrayList<>();
  * assertEquals(myMaps, ImmutableList.of(ImmutableMap.of()));
  * }</pre>
- *
- * <p>A few {@link Assert} methods are not rewritten:
- *
- * <ul>
- *   <li>These methods cannot (easily) be expressed using AssertJ because they mix regular equality
- *       and array equality:
- *       <ul>
- *         <li>{@link Assert#assertEqualsDeep(Map, Map)}
- *         <li>{@link Assert#assertEqualsDeep(Map, Map, String)}
- *         <li>{@link Assert#assertEqualsDeep(Set, Set, String)}
- *         <li>{@link Assert#assertNotEqualsDeep(Map, Map)}
- *         <li>{@link Assert#assertNotEqualsDeep(Map, Map, String)}
- *         <li>{@link Assert#assertNotEqualsDeep(Set, Set)}
- *         <li>{@link Assert#assertNotEqualsDeep(Set, Set, String)}
- *       </ul>
- *   <li>This method returns the caught exception; there is no direct counterpart for this in
- *       AssertJ:
- *       <ul>
- *         <li>{@link Assert#expectThrows(Class, ThrowingRunnable)}
- *       </ul>
- * </ul>
  */
 // XXX: As-is these rules do not result in a complete migration:
 // - Expressions containing comments are skipped due to a limitation of Refaster.
 // - Assertions inside lambda expressions are also skipped. Unclear why.
+// XXX: The `assertEquals` tests for this class generally use the same expression for `expected` and
+// `actual`, which makes the validation weaker than necessary; fix this. (And investigate whether we
+// can introduce validation for this.)
 @OnlineDocumentation
+@TypeMigration(
+    of = Assert.class,
+    unmigratedMethods = {
+      // XXX: Add migrations for the methods below.
+      "assertEquals(Boolean, Boolean)",
+      "assertEquals(Boolean, boolean)",
+      "assertEquals(boolean, Boolean)",
+      "assertEquals(Boolean, Boolean, String)",
+      "assertEquals(Boolean, boolean, String)",
+      "assertEquals(boolean, Boolean, String)",
+      "assertEquals(Byte, Byte)",
+      "assertEquals(Byte, byte)",
+      "assertEquals(byte, Byte)",
+      "assertEquals(Byte, Byte, String)",
+      "assertEquals(Byte, byte, String)",
+      "assertEquals(byte, Byte, String)",
+      "assertEquals(char, Character)",
+      "assertEquals(char, Character, String)",
+      "assertEquals(Character, char)",
+      "assertEquals(Character, char, String)",
+      "assertEquals(Character, Character)",
+      "assertEquals(Character, Character, String)",
+      "assertEquals(Double, Double)",
+      "assertEquals(Double, double)",
+      "assertEquals(double, Double)",
+      "assertEquals(Double, Double, String)",
+      "assertEquals(Double, double, String)",
+      "assertEquals(double, Double, String)",
+      "assertEquals(double[], double[], double)",
+      "assertEquals(double[], double[], double, String)",
+      "assertEquals(Float, Float)",
+      "assertEquals(Float, float)",
+      "assertEquals(float, Float)",
+      "assertEquals(Float, Float, String)",
+      "assertEquals(Float, float, String)",
+      "assertEquals(float, Float, String)",
+      "assertEquals(float[], float[], float)",
+      "assertEquals(float[], float[], float, String)",
+      "assertEquals(int, Integer)",
+      "assertEquals(int, Integer, String)",
+      "assertEquals(Integer, int)",
+      "assertEquals(Integer, int, String)",
+      "assertEquals(Integer, Integer)",
+      "assertEquals(Integer, Integer, String)",
+      "assertEquals(Long, Long)",
+      "assertEquals(Long, long)",
+      "assertEquals(long, Long)",
+      "assertEquals(Long, Long, String)",
+      "assertEquals(Long, long, String)",
+      "assertEquals(Short, Short)",
+      "assertEquals(Short, short)",
+      "assertEquals(short, Short)",
+      "assertEquals(Short, Short, String)",
+      "assertEquals(Short, short, String)",
+      "assertEquals(short, Short, String)",
+      /*
+       * These `assertEqualsDeep` methods cannot (easily) be expressed using AssertJ because they
+       * mix regular equality and array equality:
+       */
+      "assertEqualsDeep(Map<?, ?>, Map<?, ?>)",
+      "assertEqualsDeep(Map<?, ?>, Map<?, ?>, String)",
+      "assertEqualsDeep(Set<?>, Set<?>, String)",
+      // XXX: Add migrations for the methods below.
+      "assertEqualsNoOrder(Collection<?>, Collection<?>)",
+      "assertEqualsNoOrder(Collection<?>, Collection<?>, String)",
+      "assertEqualsNoOrder(Iterator<?>, Iterator<?>)",
+      "assertEqualsNoOrder(Iterator<?>, Iterator<?>, String)",
+      "assertListContains(List<T>, Predicate<T>, String)",
+      "assertListContainsObject(List<T>, T, String)",
+      "assertListNotContains(List<T>, Predicate<T>, String)",
+      "assertListNotContainsObject(List<T>, T, String)",
+      "assertNotEquals(Collection<?>, Collection<?>)",
+      "assertNotEquals(Collection<?>, Collection<?>, String)",
+      "assertNotEquals(Iterator<?>, Iterator<?>)",
+      "assertNotEquals(Iterator<?>, Iterator<?>, String)",
+      "assertNotEquals(Object[], Object[], String)",
+      /*
+       * These `assertNotEqualsDeep` methods cannot (easily) be expressed using AssertJ because they
+       * mix regular equality and array equality:
+       */
+      "assertNotEqualsDeep(Map<?, ?>, Map<?, ?>)",
+      "assertNotEqualsDeep(Map<?, ?>, Map<?, ?>, String)",
+      "assertNotEqualsDeep(Set<?>, Set<?>)",
+      "assertNotEqualsDeep(Set<?>, Set<?>, String)",
+      // XXX: Add a migration for this `assertThrows` method.
+      "assertThrows(String, Class<T>, ThrowingRunnable)",
+      /*
+       * These `expectThrows` methods return the caught exception; there is no direct counterpart
+       * for this in AssertJ.
+       */
+      "expectThrows(Class<T>, ThrowingRunnable)",
+      "expectThrows(String, Class<T>, ThrowingRunnable)"
+    })
 final class TestNGToAssertJRules {
   private TestNGToAssertJRules() {}
 
@@ -85,8 +161,9 @@ final class TestNGToAssertJRules {
 
     @AfterTemplate
     @DoNotCall
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
     void after() {
-      throw new AssertionError();
+      fail();
     }
   }
 

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

@@ -0,0 +1,80 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import com.google.errorprone.CompilationTestHelper;
+import org.junit.jupiter.api.Test;
+
+final class EmptyMonoZipTest {
+  @Test
+  void identification() {
+    CompilationTestHelper.newInstance(EmptyMonoZip.class, getClass())
+        .expectErrorMessage(
+            "ARGUMENT",
+            m ->
+                m.contains(
+                    "Don't pass a `Mono<Void>` or `Mono.empty()` argument to `Mono#{zip,With}`"))
+        .expectErrorMessage(
+            "RECEIVER",
+            m ->
+                m.contains(
+                    "Invoking `Mono#zipWith` on `Mono#empty()` or a `Mono<Void>` is a no-op"))
+        .addSourceLines(
+            "A.java",
+            "import static reactor.core.publisher.Mono.zip;",
+            "",
+            "import reactor.core.publisher.Flux;",
+            "import reactor.core.publisher.Mono;",
+            "",
+            "class A {",
+            "  void m() {",
+            "    Flux.just(1).zip(Mono.empty(), Flux.just(2));",
+            "",
+            "    Mono<Void> voidMono = Mono.empty();",
+            "    Mono<Integer> integerMono = Mono.empty();",
+            "",
+            "    zip(Mono.just(1), Mono.just(2));",
+            "    Mono.zip(Mono.just(1), Mono.just(2));",
+            "    Mono.zip(Mono.just(1), Mono.just(2), Mono.just(3));",
+            "    Mono.zip(integerMono, integerMono);",
+            "",
+            "    // BUG: Diagnostic matches: ARGUMENT",
+            "    zip(Mono.empty(), Mono.empty());",
+            "    // BUG: Diagnostic matches: ARGUMENT",
+            "    Mono.zip(Mono.empty(), Mono.empty());",
+            "    // BUG: Diagnostic matches: ARGUMENT",
+            "    Mono.zip(voidMono, Mono.just(1));",
+            "    // BUG: Diagnostic matches: ARGUMENT",
+            "    Mono.zip(voidMono, voidMono);",
+            "    // BUG: Diagnostic matches: ARGUMENT",
+            "    Mono.zip(Mono.just(1).then(), Mono.just(2));",
+            "    // BUG: Diagnostic matches: ARGUMENT",
+            "    Mono.zip(Mono.just(1), Mono.just(2), voidMono);",
+            "",
+            "    Mono.just(1).zipWith(Mono.just(2));",
+            "    Mono.just(1).zipWith(integerMono);",
+            "    Mono.just(1).zipWith(integerMono, (a, b) -> a + b);",
+            "",
+            "    // BUG: Diagnostic matches: ARGUMENT",
+            "    Mono.just(1).zipWith(Mono.empty());",
+            "    // BUG: Diagnostic matches: ARGUMENT",
+            "    Mono.just(1).zipWith(voidMono);",
+            "    // BUG: Diagnostic matches: RECEIVER",
+            "    Mono.empty().zipWith(Mono.just(1));",
+            "    // BUG: Diagnostic matches: RECEIVER",
+            "    voidMono.zipWith(Mono.just(1));",
+            "  }",
+            "",
+            "  abstract class MyMono extends Mono<Object> {",
+            "    void m() {",
+            "      zip(Mono.just(1), Mono.just(2));",
+            "      // BUG: Diagnostic matches: ARGUMENT",
+            "      zip(Mono.empty(), Mono.empty());",
+            "",
+            "      zipWith(Mono.just(1));",
+            "      // BUG: Diagnostic matches: ARGUMENT",
+            "      zipWith(Mono.empty());",
+            "    }",
+            "  }",
+            "}")
+        .doTest();
+  }
+}

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

@@ -0,0 +1,135 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import com.google.errorprone.BugCheckerRefactoringTestHelper;
+import com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode;
+import com.google.errorprone.CompilationTestHelper;
+import org.junit.jupiter.api.Test;
+
+final class OptionalOrElseTest {
+  @Test
+  void identification() {
+    CompilationTestHelper.newInstance(OptionalOrElse.class, getClass())
+        .addSourceLines(
+            "A.java",
+            "import com.google.errorprone.refaster.Refaster;",
+            "import java.util.Optional;",
+            "",
+            "class A {",
+            "  private final Optional<Object> optional = Optional.empty();",
+            "  private final String string = optional.toString();",
+            "",
+            "  void m() {",
+            "    Optional.empty().orElse(null);",
+            "    optional.orElse(null);",
+            "    optional.orElse(\"constant\");",
+            "    optional.orElse(\"constant\" + 0);",
+            "    optional.orElse(Boolean.TRUE);",
+            "    optional.orElse(string);",
+            "    optional.orElse(this.string);",
+            "    optional.orElse(Refaster.anyOf(\"constant\", \"another\"));",
+            "",
+            "    // BUG: Diagnostic contains:",
+            "    Optional.empty().orElse(string + \"constant\");",
+            "    // BUG: Diagnostic contains:",
+            "    optional.orElse(string + \"constant\");",
+            "    // BUG: Diagnostic contains:",
+            "    optional.orElse(\"constant\".toString());",
+            "    // BUG: Diagnostic contains:",
+            "    optional.orElse(string.toString());",
+            "    // BUG: Diagnostic contains:",
+            "    optional.orElse(this.string.toString());",
+            "    // BUG: Diagnostic contains:",
+            "    optional.orElse(String.valueOf(42));",
+            "    // BUG: Diagnostic contains:",
+            "    optional.orElse(string.toString().length());",
+            "    // BUG: Diagnostic contains:",
+            "    optional.orElse(\"constant\".equals(string));",
+            "    // BUG: Diagnostic contains:",
+            "    optional.orElse(string.equals(string));",
+            "    // BUG: Diagnostic contains:",
+            "    optional.orElse(this.string.equals(string));",
+            "    // BUG: Diagnostic contains:",
+            "    optional.orElse(foo());",
+            "    // BUG: Diagnostic contains:",
+            "    optional.orElse(this.foo());",
+            "    // BUG: Diagnostic contains:",
+            "    optional.orElse(new Object() {});",
+            "    // BUG: Diagnostic contains:",
+            "    optional.orElse(new int[0].length);",
+            "  }",
+            "",
+            "  private <T> T foo() {",
+            "    return null;",
+            "  }",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  void replacement() {
+    BugCheckerRefactoringTestHelper.newInstance(OptionalOrElse.class, getClass())
+        .addInputLines(
+            "A.java",
+            "import java.util.Optional;",
+            "",
+            "class A {",
+            "  private final Optional<Object> optional = Optional.empty();",
+            "  private final String string = optional.toString();",
+            "",
+            "  void m() {",
+            "    optional.orElse(string + \"constant\");",
+            "    optional.orElse(\"constant\".toString());",
+            "    optional.orElse(string.toString());",
+            "    optional.orElse(this.string.toString());",
+            "    optional.orElse(String.valueOf(42));",
+            "    optional.orElse(string.toString().length());",
+            "    optional.orElse(string.equals(string));",
+            "    optional.orElse(foo());",
+            "    optional.orElse(this.<Number>foo());",
+            "    optional.orElse(this.<String, Integer>bar());",
+            "    optional.orElse(new Object() {});",
+            "    optional.orElse(new int[0].length);",
+            "  }",
+            "",
+            "  private <T> T foo() {",
+            "    return null;",
+            "  }",
+            "",
+            "  private <S, T> T bar() {",
+            "    return null;",
+            "  }",
+            "}")
+        .addOutputLines(
+            "A.java",
+            "import java.util.Optional;",
+            "",
+            "class A {",
+            "  private final Optional<Object> optional = Optional.empty();",
+            "  private final String string = optional.toString();",
+            "",
+            "  void m() {",
+            "    optional.orElseGet(() -> string + \"constant\");",
+            "    optional.orElseGet(\"constant\"::toString);",
+            "    optional.orElseGet(string::toString);",
+            "    optional.orElseGet(this.string::toString);",
+            "    optional.orElseGet(() -> String.valueOf(42));",
+            "    optional.orElseGet(() -> string.toString().length());",
+            "    optional.orElseGet(() -> string.equals(string));",
+            "    optional.orElseGet(() -> foo());",
+            "    optional.orElseGet(this::<Number>foo);",
+            "    optional.orElseGet(this::<String, Integer>bar);",
+            "    optional.orElseGet(() -> new Object() {});",
+            "    optional.orElseGet(() -> new int[0].length);",
+            "  }",
+            "",
+            "  private <T> T foo() {",
+            "    return null;",
+            "  }",
+            "",
+            "  private <S, T> T bar() {",
+            "    return null;",
+            "  }",
+            "}")
+        .doTest(TestMode.TEXT_MATCH);
+  }
+}

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/Slf4jLogStatementTest.java

@@ -19,7 +19,6 @@ final class Slf4jLogStatementTest {
             "class A {",
             "  private static final String FMT0 = \"format-string-without-placeholders\";",
             "  private static final String FMT1 = \"format-string-with-{}-placeholder\";",
-            "  private static final String FMT2 = \"format-string-with-{}-{}-placeholders\";",
             "  private static final String FMT_ERR = \"format-string-with-%s-placeholder\";",
             "  private static final Logger LOG = LoggerFactory.getLogger(A.class);",
             "",

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

@@ -1,17 +0,0 @@
-package tech.picnic.errorprone.refasterrules;
-
-import java.io.IOException;
-import java.nio.charset.StandardCharsets;
-import java.nio.file.Files;
-import java.nio.file.Paths;
-import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
-
-final class FileRulesTest implements RefasterRuleCollectionTestCase {
-  String testFilesReadStringWithCharset() throws IOException {
-    return new String(Files.readAllBytes(Paths.get("foo")), StandardCharsets.ISO_8859_1);
-  }
-
-  String testFilesReadString() throws IOException {
-    return Files.readString(Paths.get("foo"), StandardCharsets.UTF_8);
-  }
-}

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

@@ -1,17 +0,0 @@
-package tech.picnic.errorprone.refasterrules;
-
-import java.io.IOException;
-import java.nio.charset.StandardCharsets;
-import java.nio.file.Files;
-import java.nio.file.Paths;
-import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
-
-final class FileRulesTest implements RefasterRuleCollectionTestCase {
-  String testFilesReadStringWithCharset() throws IOException {
-    return Files.readString(Paths.get("foo"), StandardCharsets.ISO_8859_1);
-  }
-
-  String testFilesReadString() throws IOException {
-    return Files.readString(Paths.get("foo"));
-  }
-}

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.data.Offset.offset;

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.data.Offset.offset;

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import static org.assertj.core.api.Assertions.assertThat;
 

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.data.Offset.offset;

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import static org.assertj.core.api.Assertions.assertThat;
 

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import static org.assertj.core.api.Assertions.assertThat;
 

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.data.Offset.offset;

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import static org.assertj.core.api.Assertions.assertThat;
 

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.data.Offset.offset;

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.data.Offset.offset;

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.data.Offset.offset;

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import static org.assertj.core.api.Assertions.assertThat;
 

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import static org.assertj.core.api.Assertions.assertThat;
 

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import static org.assertj.core.api.Assertions.assertThat;
 

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import static org.assertj.core.api.Assertions.assertThat;
 

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import static org.assertj.core.api.Assertions.assertThat;
 

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.data.Offset.offset;

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import static org.assertj.core.api.Assertions.assertThat;
 

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.assertj.core.api.Assertions.assertThatIOException;

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import static com.google.common.collect.ImmutableSet.toImmutableSet;
 

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import com.google.common.collect.ImmutableSet;
 import java.math.BigDecimal;

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import com.google.common.collect.ImmutableSet;
 import com.google.errorprone.BugCheckerRefactoringTestHelper;

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

@@ -1,26 +1,34 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import com.google.common.collect.ImmutableSet;
-import java.io.IOException;
+import java.util.function.Function;
 import java.util.function.Predicate;
 import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
 
 final class ClassRulesTest implements RefasterRuleCollectionTestCase {
-  boolean testClassIsInstance() throws IOException {
+  boolean testClassIsInstance() {
     return CharSequence.class.isAssignableFrom("foo".getClass());
   }
 
-  ImmutableSet<Boolean> testInstanceof() throws IOException {
+  ImmutableSet<Boolean> testInstanceof() {
     Class<?> clazz = CharSequence.class;
     return ImmutableSet.of(CharSequence.class.isInstance("foo"), clazz.isInstance("bar"));
   }
 
-  Predicate<String> testClassLiteralIsInstancePredicate() throws IOException {
+  Predicate<String> testClassLiteralIsInstancePredicate() {
     return s -> s instanceof CharSequence;
   }
 
-  Predicate<String> testClassReferenceIsInstancePredicate() throws IOException {
+  Predicate<String> testClassReferenceIsInstancePredicate() {
     Class<?> clazz = CharSequence.class;
     return s -> clazz.isInstance(s);
   }
+
+  Function<Number, Integer> testClassLiteralCast() {
+    return i -> (Integer) i;
+  }
+
+  Function<Number, Integer> testClassReferenceCast() {
+    return i -> Integer.class.cast(i);
+  }
 }

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
@@ -6,9 +6,11 @@ import com.google.common.collect.ImmutableSortedSet;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Lists;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.LinkedList;
+import java.util.List;
 import java.util.Optional;
 import java.util.TreeSet;
 import java.util.stream.Stream;
@@ -29,7 +31,9 @@ final class CollectionRulesTest implements RefasterRuleCollectionTestCase {
         ImmutableSet.of(5).size() > 0,
         ImmutableSet.of(6).size() >= 1,
         Iterables.isEmpty(ImmutableSet.of(7)),
-        ImmutableSet.of(8).asList().isEmpty());
+        ImmutableSet.of(8).stream().findAny().isEmpty(),
+        ImmutableSet.of(9).stream().findFirst().isEmpty(),
+        ImmutableSet.of(10).asList().isEmpty());
   }
 
   ImmutableSet<Integer> testCollectionSize() {
@@ -68,6 +72,10 @@ final class CollectionRulesTest implements RefasterRuleCollectionTestCase {
     }
   }
 
+  Stream<Integer> testSetStream() {
+    return ImmutableSet.of(1).stream().distinct();
+  }
+
   ArrayList<String> testNewArrayListFromCollection() {
     return Lists.newArrayList(ImmutableList.of("foo"));
   }
@@ -92,6 +100,10 @@ final class CollectionRulesTest implements RefasterRuleCollectionTestCase {
     return ImmutableSet.of(1).asList().toString();
   }
 
+  List<String> testArraysAsList() {
+    return Arrays.stream(new String[0]).toList();
+  }
+
   ImmutableSet<Object[]> testCollectionToArray() {
     return ImmutableSet.of(
         ImmutableSet.of(1).toArray(new Object[1]),

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import static java.util.Comparator.naturalOrder;
 import static java.util.Comparator.reverseOrder;
@@ -9,6 +9,7 @@ import static java.util.stream.Collectors.minBy;
 import com.google.common.collect.Comparators;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
+import java.math.RoundingMode;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.Comparator;
@@ -54,6 +55,10 @@ final class ComparatorRulesTest implements RefasterRuleCollectionTestCase {
         Comparator.comparing(s -> "foo", Comparator.comparingInt(String::length)));
   }
 
+  Comparator<String> testComparingEnum() {
+    return Comparator.comparingInt(s -> RoundingMode.valueOf(s).ordinal());
+  }
+
   Comparator<String> testThenComparing() {
     return Comparator.<String>naturalOrder().thenComparing(Comparator.comparing(String::isEmpty));
   }
@@ -102,6 +107,14 @@ final class ComparatorRulesTest implements RefasterRuleCollectionTestCase {
         Comparator.<String>reverseOrder().compare("baz", "qux"));
   }
 
+  String testMinOfArray() {
+    return Arrays.stream(new String[0]).min(naturalOrder()).orElseThrow();
+  }
+
+  String testMinOfCollection() {
+    return ImmutableSet.of("foo", "bar").stream().min(naturalOrder()).orElseThrow();
+  }
+
   int testMinOfVarargs() {
     return Stream.of(1, 2).min(naturalOrder()).orElseThrow();
   }
@@ -130,6 +143,14 @@ final class ComparatorRulesTest implements RefasterRuleCollectionTestCase {
         Collections.min(ImmutableSet.of("a", "b"), (a, b) -> 1));
   }
 
+  String testMaxOfArray() {
+    return Arrays.stream(new String[0]).max(naturalOrder()).orElseThrow();
+  }
+
+  String testMaxOfCollection() {
+    return ImmutableSet.of("foo", "bar").stream().max(naturalOrder()).orElseThrow();
+  }
+
   int testMaxOfVarargs() {
     return Stream.of(1, 2).max(naturalOrder()).orElseThrow();
   }
@@ -173,4 +194,16 @@ final class ComparatorRulesTest implements RefasterRuleCollectionTestCase {
   Collector<Integer, ?, Optional<Integer>> testMaxByNaturalOrder() {
     return minBy(reverseOrder());
   }
+
+  ImmutableSet<Boolean> testIsLessThan() {
+    return ImmutableSet.of(
+        RoundingMode.UP.ordinal() < RoundingMode.DOWN.ordinal(),
+        RoundingMode.UP.ordinal() >= RoundingMode.DOWN.ordinal());
+  }
+
+  ImmutableSet<Boolean> testIsLessThanOrEqualTo() {
+    return ImmutableSet.of(
+        RoundingMode.UP.ordinal() <= RoundingMode.DOWN.ordinal(),
+        RoundingMode.UP.ordinal() > RoundingMode.DOWN.ordinal());
+  }
 }

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Streams;

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

@@ -1,5 +1,6 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
+import static java.util.function.Predicate.isEqual;
 import static java.util.function.Predicate.not;
 
 import com.google.common.collect.BoundType;
@@ -14,15 +15,21 @@ import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
 final class EqualityRulesTest implements RefasterRuleCollectionTestCase {
   @Override
   public ImmutableSet<Object> elidedTypesAndStaticImports() {
-    return ImmutableSet.of(Objects.class, Optional.class, not(null));
+    return ImmutableSet.of(Objects.class, Optional.class, isEqual(null), not(null));
   }
 
-  ImmutableSet<Boolean> testPrimitiveOrReferenceEquality() {
+  ImmutableSet<Boolean> testEnumReferenceEquality() {
     return ImmutableSet.of(
         RoundingMode.UP.equals(RoundingMode.DOWN),
         Objects.equals(RoundingMode.UP, RoundingMode.DOWN),
+        RoundingMode.UP.ordinal() == RoundingMode.DOWN.ordinal(),
         !RoundingMode.UP.equals(RoundingMode.DOWN),
-        !Objects.equals(RoundingMode.UP, RoundingMode.DOWN));
+        !Objects.equals(RoundingMode.UP, RoundingMode.DOWN),
+        RoundingMode.UP.ordinal() != RoundingMode.DOWN.ordinal());
+  }
+
+  ImmutableSet<Predicate<RoundingMode>> testEnumReferenceEqualityLambda() {
+    return ImmutableSet.of(isEqual(RoundingMode.DOWN), RoundingMode.UP::equals);
   }
 
   boolean testEqualsPredicate() {

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

@@ -0,0 +1,42 @@
+package tech.picnic.errorprone.refasterrules.input;
+
+import com.google.common.collect.ImmutableSet;
+import java.io.File;
+import java.io.IOException;
+import java.net.URI;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
+
+final class FileRulesTest implements RefasterRuleCollectionTestCase {
+  Path testPathOfUri() {
+    return Paths.get(URI.create("foo"));
+  }
+
+  ImmutableSet<Path> testPathOfString() {
+    return ImmutableSet.of(Paths.get("foo"), Paths.get("bar", "baz", "qux"));
+  }
+
+  Path testPathInstance() {
+    return Path.of("foo").toFile().toPath();
+  }
+
+  String testFilesReadStringWithCharset() throws IOException {
+    return new String(Files.readAllBytes(Paths.get("foo")), StandardCharsets.ISO_8859_1);
+  }
+
+  String testFilesReadString() throws IOException {
+    return Files.readString(Paths.get("foo"), StandardCharsets.UTF_8);
+  }
+
+  ImmutableSet<File> testFilesCreateTempFileToFile() throws IOException {
+    return ImmutableSet.of(
+        File.createTempFile("foo", "bar"), File.createTempFile("baz", "qux", null));
+  }
+
+  File testFilesCreateTempFileInCustomDirectoryToFile() throws IOException {
+    return File.createTempFile("foo", "bar", new File("baz"));
+  }
+}

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import static com.google.common.collect.ImmutableListMultimap.flatteningToImmutableListMultimap;
 import static com.google.common.collect.ImmutableListMultimap.toImmutableListMultimap;

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import static com.google.common.collect.ImmutableList.toImmutableList;
 import static java.util.Comparator.naturalOrder;

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

@@ -1,4 +1,4 @@
-package tech.picnic.errorprone.refasterrules;
+package tech.picnic.errorprone.refasterrules.input;
 
 import static com.google.common.collect.ImmutableMap.toImmutableMap;
 import static java.util.function.Function.identity;