Check API compatibility workflow (google/gson)

# This workflow makes sure that a pull request does not make any incompatible changes
# to the public API of Gson
name: Check API compatibility
 
on: pull_request
permissions:
  contents: read #  to fetch code (actions/checkout)
 
env:
  # Common Maven arguments
  MAVEN_ARGS: --show-version --batch-mode --no-transfer-progress
 
concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true
 
jobs:
  check-api-compatibility:
    timeout-minutes: 30
    runs-on: latchkey-small
 
    # This setup tries to determine API incompatibility only for the changes introduced by the
    # pull request. It does this by first checking out the 'old' version and installing it into
    # the local Maven repository before then using japicmp to compare it to the current changes.
    #
    # Alternatively it would also be possible to compare against the last release version instead.
    #
    # Both approaches have their advantages and disadvantages, see description of
    # https://github.com/google/gson/pull/2692 for details.
 
    steps:
      - name: Check out old version
        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd  # v6.0.2
        with:
          ref: ${{ github.event.pull_request.base.sha }}
          path: 'gson-old-japicmp'
 
      - name: Set up JDK
        uses: actions/setup-java@be666c2fcd27ec809703dec50e508c2fdc7f6654  # v5.2.0
        with:
          distribution: 'temurin'
          java-version: '17'
          cache: 'maven'
 
      - name: Build old version
        run: |
          cd gson-old-japicmp
          # Set dummy version
          mvn org.codehaus.mojo:versions-maven-plugin:2.16.2:set "-DnewVersion=0.0.0-JAPICMP-OLD"
          # Install artifacts with dummy version in local repository; used later by Maven plugin for comparison
          mvn install -Dmaven.test.skip --projects '!metrics,!test-graal-native-image,!test-jpms,!test-shrinker'
 
      - name: Check out new version
        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd  # v6.0.2
 
      - name: Check API compatibility
        id: check-compatibility
        run: |
          mvn package japicmp:cmp --fail-at-end -Dmaven.test.skip --projects '!extras,!metrics,!test-graal-native-image,!test-jpms,!test-shrinker'
 
      - name: Upload API differences artifacts
        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a  # v7.0.1
        # Run on workflow success (in that case differences report might include added methods and classes)
        # or when API compatibility check failed
        if: success() || ( failure() && steps.check-compatibility.outcome == 'failure' )
        with:
          name: api-differences
          path: |
            **/japicmp/default-cli.html
            **/japicmp/default-cli.diff
          # Plugin should always have created report files (though they might be empty)
          if-no-files-found: error