code: public static <T> Callback<T> convertPromise(final Reactor reactor, final Promise<T> promise) {
          return convertPromiseToCallback(promise, reactor.callbackBuilder());
      }
docs: Converts a Reakt promise into a QBit callback.
  Reactor is used to manage timeouts and ensure callback happens on same thread as caller.
  
  @param reactor QBit reactor
  @param promise reakt promise
  @param <T>     type of promise
  @return new QBit callback that wraps promise.