Add spotless auto-fix for PRs

.github/workflows/auto-spotless.yml

@@ -0,0 +1,111 @@
+name: Auto spotless
+on:
+  pull_request_target:
+    types:
+      - opened
+      - synchronize
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    outputs:
+      patch-created: ${{ steps.create-patch-file.outputs.nonempty }}
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+
+      - name: Free disk space
+        run: .github/scripts/gha-free-disk-space.sh
+
+      - name: Set up JDK for running Gradle
+        uses: actions/setup-java@c5195efecf7bdfc987ee8bae7a71cb8b11521c00 # v4.7.1
+        with:
+          distribution: temurin
+          java-version-file: .java-version
+
+      - name: Setup Gradle
+        uses: gradle/actions/setup-gradle@06832c7b30a0129d7fb559bcc6e43d26f6374244 # v4.3.1
+        with:
+          cache-read-only: true
+
+      - name: Check out PR branch
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: gh pr checkout ${{ github.event.pull_request.number }}
+
+      - name: Spotless
+        run: ./gradlew spotlessApply
+
+      - id: create-patch-file
+        name: Create patch file
+        run: |
+          git diff > patch
+          if [ -s patch ]; then
+            echo "nonempty=true" >> "$GITHUB_OUTPUT"
+          fi
+
+      - name: Upload patch file
+        if: steps.create-patch-file.outputs.nonempty == 'true'
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
+        with:
+          path: patch
+          name: patch
+
+  apply:
+    runs-on: ubuntu-latest
+    needs: check
+    if: needs.check.outputs.patch-created == 'true'
+    permissions:
+      contents: write
+      pull-requests: write
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+
+      - name: Check out PR branch
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: gh pr checkout ${{ github.event.pull_request.number }}
+
+      - name: Download patch
+        uses: actions/download-artifact@v4
+        with:
+          name: patch
+
+      - name: Use CLA approved github bot
+        # IMPORTANT do not call the .github/scripts/use-cla-approved-bot.sh
+        # since that script could have been compromised in the PR branch
+        run: |
+          git config user.name otelbot
+          git config user.email [email protected]
+
+      - uses: actions/create-github-app-token@df432ceedc7162793a195dd1713ff69aefc7379e # v2.0.6
+        id: otelbot-token
+        with:
+          app-id: ${{ vars.OTELBOT_APP_ID }}
+          private-key: ${{ secrets.OTELBOT_PRIVATE_KEY }}
+
+      - name: Apply patch and push
+        env:
+          GH_TOKEN: ${{ steps.otelbot-token.outputs.token }}
+        run: |
+          git apply patch
+          git commit -a -m "./gradlew spotlessApply"
+          git push
+
+      - if: success()
+        env:
+          GH_TOKEN: ${{ steps.otelbot-token.outputs.token }}
+        run: |
+          gh pr comment $PR_NUM --body "🔧 The result from \`./gradlew spotlessApply\` was committed to the PR branch."
+
+      - if: failure()
+        env:
+          GH_TOKEN: ${{ steps.otelbot-token.outputs.token }}
+        run: |
+          gh pr comment $PR_NUM --body "❌ The result from \`./gradlew spotlessApply\` could not be committed to the PR branch, see logs: $GITHUB_SERVER_URL/$GITHUB_REPOSITORY/actions/runs/$GITHUB_RUN_ID."