code: public PubsubFuture<Void> acknowledge(final String project, final String subscription, final List<String> ackIds) {
      return acknowledge(Subscription.canonicalSubscription(project, subscription), ackIds);
    }
docs: Acknowledge a batch of received messages.
  
  @param project      The Google Cloud project.
  @param subscription The subscription to acknowledge messages on.
  @param ackIds       List of message ID's to acknowledge.
  @return A future that is completed when this request is completed.