Post code suggestions on PRs with format issues

Author: timtebeek

.github/workflows/pr-format-workflow.yml

@@ -0,0 +1,55 @@
+# Description: This workflow applies the formatter against the opened pull request and upload the patch.
+# Since this pull request receives untrusted code, we should **NOT** have any secrets in the environment.
+# https://securitylab.github.com/research/github-actions-preventing-pwn-requests/
+---
+name: pr-format-workflow
+
+on:
+  pull_request:
+    types: [opened, synchronize]
+    branches:
+      - main
+
+concurrency:
+  group: '${{ github.workflow }} @ ${{ github.ref }}'
+  cancel-in-progress: true
+
+jobs:
+  upload-patch:
+    runs-on: ubuntu-latest
+    if: ${{ github.repository == 'spring-projects/spring-security' }}
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          ref: ${{github.event.pull_request.head.ref}}
+          repository: ${{github.event.pull_request.head.repo.full_name}}
+      - name: Set up gradle
+        uses: spring-io/spring-gradle-build-action@v2
+        with:
+          java-version: '17'
+          distribution: 'temurin'
+
+      # Capture the PR number
+      # https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#using-data-from-the-triggering-workflow
+      - name: Create pr_number.txt
+        run: echo "${{ github.event.number }}" > pr_number.txt
+      - uses: actions/upload-artifact@v4
+        with:
+          name: pr_number
+          path: pr_number.txt
+      - name: Remove pr_number.txt
+        run: rm -f pr_number.txt
+
+      # Format code
+      - name: Format with Gradle
+        run: ./gradlew format
+
+      # Capture the diff
+      - name: Create patch
+        run: |
+          git diff | tee git-diff.patch
+      - uses: actions/upload-artifact@v4
+        with:
+          name: patch
+          path: git-diff.patch

.github/workflows/pr-suggestions-workflow.yml

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+# Description: This workflow is triggered when the `pr-format-workflow` completes to post suggestions on the PR.
+# Since this pull request has write permissions on the target repo, we should **NOT** execute any untrusted code.
+# https://securitylab.github.com/research/github-actions-preventing-pwn-requests/
+---
+name: pr-suggestions-workflow
+
+on:
+  workflow_run:
+    workflows: ["pr-format-workflow"]
+    types:
+      - completed
+
+jobs:
+  post-suggestions:
+    # https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#running-a-workflow-based-on-the-conclusion-of-another-workflow
+    if: ${{ github.event.workflow_run.conclusion == 'success' }}
+    runs-on: ubuntu-latest
+    permissions:
+      actions: read
+      pull-requests: write
+    env:
+      # https://docs.github.com/en/actions/reference/authentication-in-a-workflow#permissions-for-the-github_token
+      ACCESS_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          ref: ${{github.event.workflow_run.head_branch}}
+          repository: ${{github.event.workflow_run.head_repository.full_name}}
+
+      # Download the patch
+      - uses: actions/download-artifact@v4
+        with:
+          name: patch
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          run-id: ${{ github.event.workflow_run.id }}
+      - name: Apply patch
+        run: |
+          git apply git-diff.patch --allow-empty
+          rm git-diff.patch
+
+      # Download the PR number
+      - uses: actions/download-artifact@v4
+        with:
+          name: pr_number
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          run-id: ${{ github.event.workflow_run.id }}
+      - name: Read pr_number.txt
+        run: |
+          PR_NUMBER=$(cat pr_number.txt)
+          echo "PR_NUMBER=$PR_NUMBER" >> $GITHUB_ENV
+          rm pr_number.txt
+
+      # Post suggestions as a comment on the PR
+      - uses: googleapis/code-suggester@v4
+        with:
+          command: review
+          pull_number: ${{ env.PR_NUMBER }}
+          git_dir: '.'