ConnectableObservable and
 GroupedObservable.See: Description
| Class | Description | 
|---|---|
| ConnectableObservable<T> | 
 A  
ConnectableObservable resembles an ordinary Observable, except that it does not begin
 emitting items when it is subscribed to, but only when its ConnectableObservable.connect(io.reactivex.functions.Consumer<? super io.reactivex.disposables.Disposable>) method is called. | 
| GroupedObservable<K,T> | 
 An  
Observable that has been grouped by key, the value of which can be obtained with getKey(). | 
ConnectableObservable and
 GroupedObservable.