GitHub Actions: cache gradle wrapper; fixed key for caching gradle cache

.github/workflows/ci.yml

@@ -15,15 +15,24 @@ jobs:
 
     steps:
     - uses: actions/checkout@v2
+
     - name: Set up JDK 1.8
       uses: actions/setup-java@v1
       with:
         java-version: 1.8
-    - name: Cache Gradle packages
+
+    - name: Cache Gradle wrapper
+      uses: actions/cache@v1
+      with:
+        path: ~/.gradle/wrapper
+        key: ${{ runner.os }}-gradle-wrapper-${{ hashFiles('gradle/wrapper/gradle-wrapper.properties') }}
+
+    - name: Cache Gradle cache
       uses: actions/cache@v2
       with:
         path: ~/.gradle/caches
-        key: ${{ runner.os }}-gradle-${{ hashFiles('**/*.gradle') }}
+        key: ${{ runner.os }}-gradle-${{ hashFiles('**/*.gradle.kts') }}
         restore-keys: ${{ runner.os }}-gradle
+
     - name: Build with Gradle
       run: ./gradlew build