anchor.diff:  }
   ----
   
  -===== Error Handling
  +====== Error Handling
   
   If you want to have more control over message processing in case of an error, you need to associate the `PubSubInboundChannelAdapter` with a Spring Integration error channel and specify the behavior to be invoked with `@ServiceActivator`.
   
  
positive.code: Each subscription has a default `ackDeadline` applied to all messages sent to it.
  Additionally, the Cloud Pub/Sub client library can extend each streamed message's `ackDeadline` until the message processing completes, fails or until the maximum extension period elapses.
  
  NOTE: In Pub/Sub client library, default maximum extension period is an hour. However, Spring Cloud GCP disables this auto-extension behavior.
  Use the `spring.cloud.gcp.pubsub.subscriber.max-ack-extension-period` property to re-enable it.
  
  Acknowledging (acking) a message removes it from Pub/Sub's known outstanding messages. Nacking a message resets its acknowledgement deadline to 0, forcing immediate redelivery.
  This could be useful in a load balanced architecture, where one of the subscribers is having issues but others are available to process messages.
  
  The `PubSubInboundChannelAdapter` supports three acknowledgement modes, with `AckMode.AUTO` being the default value: `AckMode.AUTO` (automatic acking and nacking), `AckMode.AUTO_ACK` (automatic acking only) and `AckMode.MANUAL` (manual acking and nacking).
  
  .Acknowledgement mode behavior
  |===
  
negative.code: }
  ----
  
  If you would prefer to manually ack or nack the message, you can do it by retrieving the header of the exception payload:
  
  [source,java]
  ----
  