code: protected void throttleOutgoingMessage ()
      {
          Throttle throttle = _client.getOutgoingMessageThrottle();
          synchronized(throttle) {
              while (throttle.throttleOp()) {
                  try {
                      Thread.sleep(2);
                  } catch (InterruptedException ie) {
                      // no problem
                  }
              }
          }
      }
docs: Throttles an outgoing message operation in a thread-safe manner.