Feel free to add more copy-paste guides
Observable is Flowable
CompositeSubscription is CompositeDisposable
Subscription is Disposable
Observable.subscribe(Observer) is Observable.subscribeWith(DisposableSubscriber) (if you want it to return a disposable)
Observable.Transformer<T,T> is FlowableTransformer<T,T>
Action1 is Consumer
Action2 is BiConsumer
Action0 is Action
Actions.empty() is Functions.EMPTY_ACTION
Similarly there are Functions.emptyConsumer and Functions.emptyBiconsumer
TestSubscription.getNextEvents() is TestSubscription.values