add ci flow

Author: ldetmer

.github/workflows/ci.yaml

@@ -0,0 +1,45 @@
+# Copyright 2022 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# Github action job to test core java library features on
+# downstream client libraries before they are released.
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+name: ci
+jobs:
+  units:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        java: [8]
+    steps:
+      - name: Get current week within the year
+        id: date
+        run: echo "::set-output name=week_of_year::$(date +'%W' --utc)"
+      - uses: actions/checkout@v4
+      - uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: 11
+          cache: maven
+      - run: java -version
+      - name: Install Maven modules to local Maven repository
+        run: |
+          mvn install -B -ntp  -T 1C -DskipTests -Dclirr.skip -Dcheckstyle.skip
+      - run: java -version
+      - run: mvn -B -ntp enforcer:enforce@enforce -T 1C
+