Enable Java CI workflow

.github/workflows/ci.yml

@@ -0,0 +1,25 @@
+
+name: Java CI
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest, macOS-latest]
+      fail-fast: false
+
+    runs-on: ${{ matrix.os }}
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-java@v2
+        with:
+          java-version: 11
+          distribution: 'temurin'
+          cache: 'maven'
+
+      - name: Build with Maven
+        run: mvn verify -e -B -V
+