code: public void addSubscribers(Subscribers subscribers) throws IOException {
          String payload = gson.toJson(subscribers);
          IronReader reader = client.post("queues/" + name + "/subscribers", payload);
          reader.close();
      }
docs: Add subscribers to Queue. If there is no queue, an EmptyQueueException is thrown.
  @param subscribers The array of subscribers.
  @throws io.iron.ironmq.HTTPException If the IronMQ service returns a status other than 200 OK.
  @throws java.io.IOException If there is an error accessing the IronMQ server.