No subscribeToTopic listener in Flutter?

[TillCity]

The Firebase documentation indicates that it is possible to tune in to subscription completion events via a Listener. However, this capability (not at all sure how it works with iOS) does not appear to have been implemented in the Flutter plugin where it appears that all one can do is make a subscribeToTopic call and hope that it all goes well. Is this correct or am I missing something in the API Docs?