code: public Boolean ack(String taskId, String workerId) {
          Preconditions.checkArgument(StringUtils.isNotBlank(taskId), "Task id cannot be blank");
  
          String response = postForEntity("tasks/{taskId}/ack", null, new Object[]{"workerid", workerId}, String.class, taskId);
          return Boolean.valueOf(response);
      }
docs: Ack for the task poll.
  
  @param taskId   Id of the task to be polled
  @param workerId user identified worker.
  @return true if the task was found with the given ID and acknowledged. False otherwise. If the server returns false, the client should NOT attempt to ack again.