code: public void acknowledge(AgentID agentId, TaskID taskId, ByteString uuid) {
      Builder acknowledge = build()
          .setAcknowledge(Acknowledge.newBuilder().setAgentId(agentId).setTaskId(taskId).setUuid(uuid));
      sendCall(acknowledge, Type.ACKNOWLEDGE);
    }
docs: Sent by the scheduler to acknowledge a status update. Note that with the new API, schedulers are responsible
  for explicitly acknowledging the receipt of status updates that have status.uuid set. These status updates
  are retried until they are acknowledged by the scheduler. The scheduler must not acknowledge status updates
  that do not have status.uuid set, as they are not retried. The uuid field contains raw bytes encoded in Base64.
  
  @param agentId
  @param taskId
  @param uuid