code: public PubsubFuture<Void> modifyAckDeadline(final String canonicalSubscriptionName, final int ackDeadlineSeconds,
                                                final List<String> ackIds) {
      final String path = canonicalSubscriptionName + ":modifyAckDeadline";
      final ModifyAckDeadlineRequest req = ModifyAckDeadlineRequest.builder()
          .ackDeadlineSeconds(ackDeadlineSeconds)
          .ackIds(ackIds)
          .build();
      return post("modify ack deadline", path, req, VOID);
    }
docs: Modify the ack deadline for a list of received messages.
  
  @param canonicalSubscriptionName The canonical (including project name) subscription of the received message to
  modify the ack deadline on.
  @param ackDeadlineSeconds        The new ack deadline.
  @param ackIds                    List of message ID's to modify the ack deadline on.
  @return A future that is completed when this request is completed.