Create simple CI workflow

.github/workflows/maven.yml

@@ -0,0 +1,40 @@
+name: Java CI with Maven
+
+on:
+  push:
+    branches: [ "master" ]
+  pull_request:
+    branches: [ "master" ]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up JDK 17
+        uses: actions/setup-java@v3
+        with:
+          java-version: '17'
+          distribution: 'temurin'
+          cache: maven
+      - name: Build bom
+        run: mvn clean install
+        working-directory: bom
+
+      - name: Build grpc-interface
+        run: mvn clean install
+        working-directory: grpc-interface
+
+      - name: Build order
+        run: mvn clean install
+        working-directory: order
+
+      - name: Build payment
+        run: mvn clean install
+        working-directory: payment
+
+      - name: Build shipping
+        run: mvn clean install
+        working-directory: shipping