Enable Java CI workflow

Author: mcculls

.github/workflows/build.yml

@@ -0,0 +1,30 @@
+
+name: build
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+  workflow_dispatch:
+
+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
+

README.md

@@ -8,6 +8,7 @@
 +-----------+---+-----------+-------+
 ```
 
+[![build](https://github.com/eclipse/sisu.plexus/actions/workflows/build.yml/badge.svg?event=push)](https://github.com/eclipse/sisu.plexus/actions/workflows/build.yml)
 [![maintainability](https://sonarcloud.io/api/project_badges/measure?project=org.eclipse.sisu%3Asisu-plexus&metric=sqale_rating)](https://sonarcloud.io/summary/overall?id=org.eclipse.sisu%3Asisu-plexus)
 [![license](https://img.shields.io/badge/license-EPL_1.0-blue.svg)](https://www.eclipse.org/legal/epl-v10.html)