GitHub Actions fixes.

.github/workflows/gradle.yml

@@ -15,12 +15,13 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
-    - name: Set up JDK 1.8
-      uses: actions/setup-java@v1
-      with:
-        java-version: 1.8
-    - name: Grant execute permission for gradlew
-      run: chmod +x gradlew
-    - name: Build with Gradle
-      run: ./gradlew build
+      - uses: actions/checkout@v2
+      - name: Set up JDK 11
+        uses: actions/setup-java@v2
+        with:
+          java-version: '11'
+          distribution: 'adopt'
+      - name: Grant execute permission for gradlew
+        run: chmod +x gradlew
+      - name: Build with Gradle
+        run: ./gradlew

build.gradle

@@ -3,6 +3,8 @@ apply plugin: 'maven-publish'
 apply plugin: 'maven'
 apply plugin: 'signing'
 
+defaultTasks 'clean', 'compileJava', 'test'
+
 repositories {
     mavenCentral()
 }