chore: add verify gradle samples build step

.github/workflows/build.yml

@@ -16,6 +16,25 @@ jobs:
       - uses: gradle/actions/wrapper-validation@v4
 
   build:
+    name: Validate samples
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Java
+        uses: actions/setup-java@v4
+        with:
+          distribution: 'temurin'
+          java-version: '8'
+
+      - name: Build and verify Gradle sample projects
+        run: |
+          cd examples/gradle
+          for x in $(find . -maxdepth 1 -type d -print); do
+            ./gradlew -i create-rock
+          done
+
     name: Build
     runs-on: ubuntu-latest
     steps: