code: public Message getMessageById(String id) throws IOException {
          String url = "queues/" + name + "/messages/" + id;
          IronReader reader = client.get(url);
          MessageContainer container = gson.fromJson(reader.reader, MessageContainer.class);
          reader.close();
          return container.getMessage();
      }
docs: Retrieves Message from the queue by message id. If there are no items on the queue, an
  EmptyQueueException is thrown.
  @param id The ID of the message to get.
  @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.