build: cache gradle based on java version

.github/workflows/test.yml

@@ -15,6 +15,7 @@ on:
 
 jobs:
   build-and-test-with-Java-8-and-later:
+    runs-on: ${{ matrix.os }}
     name: Build/Test (JDK ${{ matrix.java }}, ${{ matrix.os }})
     strategy:
       fail-fast: false
@@ -22,24 +23,27 @@ jobs:
       matrix:
         os: [ubuntu-latest, macOS-latest, windows-latest]
         java: [8, 9, 10, 11, 12, 13, 14]
-    runs-on: ${{ matrix.os }}
+
     steps:
       - uses: actions/cache@v2
         with:
           path: |
             ~/.gradle/caches
             ~/.gradle/wrapper
-          key: ${{ runner.os }}-gradle-${{ hashFiles('**/*.gradle*') }}
-          restore-keys: |
-            ${{ runner.os }}-gradle-
+          key: ${{ runner.os }}-gradle-${{ matrix.java }}-${{ hashFiles('**/*.gradle*') }}
+          restore-keys: ${{ runner.os }}-${{ matrix.java }}-gradle-
+
       - uses: actions/checkout@v2
+
       - name: Set up JDK ${{ matrix.java }}
         uses: actions/setup-java@v1
         with:
           java-version: ${{ matrix.java }}
+
       - name: Build and test
-        run: ./gradlew.bat build shadowJar proguard
         if: startsWith(matrix.os, 'windows') == true
+        run: ./gradlew.bat build shadowJar proguard
+
       - name: Build and test
+        if: startsWith(matrix.os, 'windows') != true
         run: ./gradlew build shadowJar proguard
-        if: startsWith(matrix.os, 'windows') != true