fix: examples main class and compile examples in CI

.github/workflows/ci.yml

@@ -69,3 +69,25 @@ jobs:
         with:
           name: test-results
           path: build/test-results/test/
+
+  examples:
+    name: Compile Examples
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v7
+
+      - name: Set up JDK 21
+        uses: actions/setup-java@v6
+        with:
+          java-version: '21'
+          distribution: 'temurin'
+
+      - name: Setup Gradle
+        uses: gradle/actions/setup-gradle@v5
+
+      - name: Publish SDK to local Maven repository
+        run: ./gradlew publishToMavenLocal -PreleaseVersion=0.0.0-local
+
+      - name: Compile examples against local SDK
+        run: mvn -B -f examples/pom.xml compile -Dpubsub-sdk.version=0.0.0-local

README.md

@@ -131,7 +131,14 @@ Standalone example programs demonstrating common patterns are in [`examples/`](e
 - `PurgeExample.java` — topic purging
 - `RetryExample.java` — custom retry configuration
 
-The examples depend on the published SDK version set in `examples/pom.xml` (`pubsub-sdk.version`). To run them against your local checkout instead:
+The examples depend on the published SDK version set in `examples/pom.xml` (`pubsub-sdk.version`). Run one by passing its main class:
+
+```sh
+cd examples
+mvn compile exec:java -Dexec.mainClass=cloud.stackit.pubsub.examples.BasicExample
+```
+
+To run them against your local checkout instead:
 
 ```sh
 ./gradlew publishToMavenLocal -PreleaseVersion=0.0.0-local

examples/pom.xml

@@ -60,9 +60,6 @@
                 <groupId>org.codehaus.mojo</groupId>
                 <artifactId>exec-maven-plugin</artifactId>
                 <version>3.4.1</version>
-                <configuration>
-                    <mainClass>cloud.stackit.pubsub.examples.Examples</mainClass>
-                </configuration>
             </plugin>
         </plugins>
     </build>