CommandGateway that returns observable/single instead of CommandCallback

DefaultObservableCommandGateway

import org.axonframework.commandhandling.CommandCallback;
import org.axonframework.commandhandling.gateway.CommandGateway;
import org.springframework.beans.factory.annotation.Autowired;
import rx.Observable;
import rx.Single;
import rx.Subscriber;

public class DefaultObservableCommandGateway implements ObservableCommandGateway {

	@Autowired
	private CommandGateway commandGateway;

	@Override
	public <R> Single<R> send(Object command) {
		return Observable.create(new Observable.OnSubscribe<R>() {
			@Override
			public void call(Subscriber<? super R> subscriber) {
				commandGateway.send(command, new CommandCallback<R>() {
					@Override
					public void onSuccess(R result) {
						if (!subscriber.isUnsubscribed()) {
							subscriber.onNext(result);
							subscriber.onCompleted();
						}
					}

					@Override
					public void onFailure(Throwable cause) {
						if (!subscriber.isUnsubscribed()) {
							subscriber.onError(cause);
						}
					}
				});
			}
		}).toSingle();
	}
}

works great with https://github.com/jmnarloch/rxjava-spring-boot-starter
to have async request with spring controller and axon.