Add support and CI tests for Java 8

.github/workflows/maven-build.yml

@@ -13,13 +13,16 @@ jobs:
   build:
 
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        java: [ '8', '11', '17' ]
 
     steps:
       - uses: actions/checkout@v2
       - name: Set up JDK 11
         uses: actions/setup-java@v2
         with:
-          java-version: '11'
+          java-version: ${{matrix.java}}
           distribution: 'adopt'
           cache: maven
       - name: Build with Maven Wrapper

.springjavaformatconfig

@@ -0,0 +1 @@
+java-baseline=8