Changed to java 8 used for standalone build

Author: YujiSoftware

.github/workflows/gradle.yml

@@ -9,6 +9,39 @@ env:
   JAVA_VERSION: '16'
 
 jobs:
+  build_jar:
+    name: Packaging for standalone.
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up JDK 8
+        uses: actions/setup-java@v2
+        with:
+          java-version: '8'
+          distribution: 'adopt'
+      - name: Cache Gradle packages
+        uses: actions/cache@v2
+        with:
+          path: |
+            ~/.gradle/caches
+            ~/.gradle/wrapper
+          key: ${{ runner.os }}-gradle-${{ hashFiles('**/*.gradle*', '**/gradle-wrapper.properties') }}
+          restore-keys: |
+            ${{ runner.os }}-gradle-
+      - name: Grant execute permission for gradlew
+        run: chmod +x gradlew
+      - name: Build with Gradle
+        run: ./gradlew assemble
+      - name: Cleanup Gradle Cache
+        run: |
+          rm -f ~/.gradle/caches/modules-2/modules-2.lock
+          rm -f ~/.gradle/caches/modules-2/gc.properties
+      - name: Upload package file
+        uses: actions/upload-artifact@v2
+        with:
+          name: artifact
+          path: build/distributions/*
+
   build_linux:
     name: Packaging for Linux.
     runs-on: ubuntu-latest
@@ -31,7 +64,7 @@ jobs:
       - name: Grant execute permission for gradlew
         run: chmod +x gradlew
       - name: Build with Gradle
-        run: ./gradlew jpackageForLinux assemble
+        run: ./gradlew jpackageForLinux
       - name: Cleanup Gradle Cache
         run: |
           rm -f ~/.gradle/caches/modules-2/modules-2.lock
@@ -40,9 +73,7 @@ jobs:
         uses: actions/upload-artifact@v2
         with:
           name: artifact
-          path: |
-            build/distributions/*
-            build/packages/*.deb
+          path: build/packages/*.deb
 
   build_mac:
     name: Packaging for macOS.