Add Java CI workflow on JDK 21

Co-Authored-By: Kyu Choi <kyuhwanchoi0423@gmail.com>

Author: devin-ai-integration[bot]

.github/workflows/gradle.yml

@@ -0,0 +1,34 @@
+name: Java CI
+
+on:
+  push:
+    branches:
+      - '**'
+    tags:
+      - 'v*' # Push events to matching v*, i.e. v1.0, v20.15.10
+  pull_request:
+    branches:
+      - '**'
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v4
+    - name: Set up JDK 21
+      uses: actions/setup-java@v4
+      with:
+        distribution: zulu
+        java-version: '21'
+    - uses: actions/cache@v4
+      with:
+        path: |
+          ~/.gradle/caches
+          ~/.gradle/wrapper
+        key: ${{ runner.os }}-gradle-${{ hashFiles('**/*.gradle*') }}
+        restore-keys: |
+          ${{ runner.os }}-gradle-
+    - name: Build with Gradle
+      run: ./gradlew clean build