if (subscribeTopicName != null && !subscribeTopicName.isEmpty()) {
Topic[] topics = {new Topic(subscribeTopicName, configuration.getQoS())};
connection.subscribe(topics, new Callback<byte[]>() {
public void onSuccess(byte[] value) {
promise.onSuccess(value);
}
public void onFailure(Throwable value) {
promise.onFailure(value);
connection.disconnect(null);