Test on all supported JDKs

.github/workflows/maven.yml

@@ -12,13 +12,16 @@ jobs:
   build:
 
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        java: [ '8', '11', '16' ] # All currently supported versions
 
     steps:
     - uses: actions/checkout@v2
-    - name: Set up JDK 8
+    - name: Set up JDK ${{ matrix.java }}
       uses: actions/setup-java@v2
       with:
-        java-version: '8'
+        java-version: ${{ matrix.java }}
         distribution: 'adopt'
     - name: Build with Maven
       run: mvn -B package --file pom.xml