Add config for GitHub action build.

.github/workflows/maven.yml

@@ -0,0 +1,25 @@
+# This workflow will build a Java project with Maven
+# For more information see: https://help.github.com/actions/language-and-framework-guides/building-and-testing-java-with-maven
+
+name: libre-wsdl4j maven build
+on:
+  push:
+    branches: [ '*' ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        java: [ 8, 11, 15 ]
+    name: Java ${{matrix.java}}
+    steps:
+      - uses: actions/checkout@v2
+      - name: Setup java
+        uses: actions/setup-java@v1
+        with:
+          java-version: ${{matrix.java}}
+      - name: Build with Maven
+        run: mvn -B package --file pom.xml