rxgroups-android/src/main/java/com/airbnb/rxgroups/GroupLifecycleManager.java
public <T> ObservableTransformer<? super T, T> transform(Observer<? super T> observer,
          String observableTag) {
    return group.transform(observer, observableTag);
  }
public <T> ObservableTransformer<? super T, T> transform(Observer<? super T> observer,
          String observableTag) {
    return group.transform(observer, observableTag);
  }
Calls {@link ObservableGroup#transform(Observer, String)}  for the group managed by
this instance.