Update GCFv2 PubSub sample (GoogleCloudPlatform#5971)

* Update GCFv2 PubSub sample

* remove unneeded attributes

* remove cloudevent pojo

* lint

* lint

Author: averikitsch

functions/v2/pubsub/subscribe-to-topic/pom.xml

@@ -44,19 +44,12 @@
       <version>1.0.4</version>
       <scope>provided</scope>
     </dependency>
-
-    <dependency>
-      <groupId>io.cloudevents</groupId>
-      <artifactId>cloudevents-api</artifactId>
-      <version>2.2.0</version>
-    </dependency>
-
     <dependency>
       <groupId>com.google.code.gson</groupId>
       <artifactId>gson</artifactId>
-      <version>2.8.7</version>
+      <version>2.8.8</version>
+      <scope>compile</scope>
     </dependency>
-
     <!-- The following dependencies are only required for testing -->
     <dependency>
       <groupId>com.google.truth</groupId>

functions/v2/pubsub/subscribe-to-topic/src/main/java/functions/SubscribeToTopic.java

@@ -17,7 +17,6 @@
 package functions;
 
 // [START functions_cloudevent_pubsub]
-
 import com.google.cloud.functions.CloudEventsFunction;
 import com.google.gson.Gson;
 import functions.eventpojos.PubSubBody;
@@ -31,13 +30,19 @@ public class SubscribeToTopic implements CloudEventsFunction {
 
   @Override
   public void accept(CloudEvent event) {
-    Gson gson = new Gson();
-    PubSubBody pubSubBody = gson.fromJson(new String(event.getData().toBytes()), PubSubBody.class);
-    String messageString =
-        new String(
-            Base64.getDecoder().decode(pubSubBody.getMessage().getData()), StandardCharsets.UTF_8);
+    logger.info("Event: " + event.getId());
+    logger.info("Event Type: " + event.getType());
 
-    logger.info(messageString);
+    if (event.getData() != null) {
+      String cloudEventData = new String(event.getData().toBytes(), StandardCharsets.UTF_8);
+      Gson gson = new Gson();
+      PubSubBody body = gson.fromJson(cloudEventData, PubSubBody.class);
+      // Retrieve PubSub message data
+      String encodedData = body.getMessage().getData();
+      String decodedData =
+          new String(Base64.getDecoder().decode(encodedData), StandardCharsets.UTF_8);
+      logger.info("Event data: " + decodedData);
+    }
   }
 }
 // [END functions_cloudevent_pubsub]

functions/v2/pubsub/subscribe-to-topic/src/test/java/functions/SubscribeToTopicTest.java

@@ -41,8 +41,8 @@ public static void beforeClass() {
 
   @Test
   public void functionsPubsubSubscribe_shouldPrintPubsubMessage() throws Exception {
-
-    String encodedMessage = Base64.getEncoder().encodeToString("Hello World".getBytes());
+    String msg = "Hello World";
+    String encodedMessage = Base64.getEncoder().encodeToString(msg.getBytes());
     String encodedData = new String("{\"message\": { \"data\": \"" + encodedMessage + "\"} }");
 
     CloudEvent event =
@@ -55,6 +55,7 @@ public void functionsPubsubSubscribe_shouldPrintPubsubMessage() throws Exception
 
     new SubscribeToTopic().accept(event);
 
-    assertThat("Hello World").isEqualTo(logHandler.getStoredLogRecords().get(0).getMessage());
+    assertThat("Event data: " + msg).isEqualTo(
+        logHandler.getStoredLogRecords().get(2).getMessage());
   }
 }