Add a bot comment that explains how to fix Spotless errors

.github/workflows/gradle.yml

@@ -1,5 +1,3 @@
-# This workflow will build a Java project with Gradle and cache/restore any dependencies to improve the workflow execution time
-# For more information see: https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-java-with-gradle
 name: Java CI with Gradle
 
 on:
@@ -17,24 +15,63 @@ on:
 jobs:
   build:
     runs-on: ubuntu-latest
+
     steps:
     - name: Checkout repository
       uses: actions/checkout@v4
+
     - name: Validate Gradle wrapper
       uses: gradle/wrapper-validation-action@v1
+
     - name: Set up Java 17
       uses: actions/setup-java@v3
       with:
         java-version: '17'
         distribution: 'microsoft'
+
     - name: Grant execute permission for gradlew
       run: chmod +x gradlew
+
     - name: Setup Gradle
       uses: gradle/gradle-build-action@v2
+
+    - name: Check code style with Spotless
+      id: spotless_check
+      run: ./gradlew spotlessCheck
+      continue-on-error: true
+
+    - name: Comment on PR on Spotless failure
+      if: ${{ steps.spotless_check.outcome == 'failure' && github.event_name == 'pull_request' }}
+      uses: actions/github-script@v7
+      with:
+        script: |
+          const prAuthor = context.payload.pull_request.user.login;
+          const codestyleUrl = `https://github.com/${context.repo.owner}/${context.repo.repo}/tree/master/codestyle`;
+          const commentBody = `
+            Hi @${prAuthor}, thanks for the pull request! It seems there are some format violations that need to be fixed.
+            
+            If you're using Eclipse, please make sure to use the cleanup and format settings located in the [codestyle folder](${codestyleUrl}). This will help ensure consistency with the existing codebase.
+            
+            Alternatively, if you're not using Eclipse, you can also fix these violations by running the following command from the command line:
+            
+            \`\`\`
+            ./gradlew spotlessApply
+            \`\`\`
+            
+            Once you've done this, please commit the changes and push them to your branch. This should cause the check to pass and allow your pull request to be merged.
+          `;
+          github.rest.issues.createComment({
+            issue_number: context.issue.number,
+            owner: context.repo.owner,
+            repo: context.repo.repo,
+            body: commentBody
+          });
+
     - name: Execute Gradle build
-      run: ./gradlew build spotlessCheck
+      run: ./gradlew build
+
     - name: VirusTotal scan
-      if: github.event_name == 'push'
+      if: ${{ github.event_name == 'push' }}
       uses: crazy-max/ghaction-virustotal@v4
       with:
         vt_api_key: ${{ secrets.VIRUSTOTAL_API_KEY }}