Request: Completable.andThen(Single)

To match Completable#andThen(Observable<T> next) it would be nice if there were an operator like this:

public <T> Single<T> andThen(Single<T> next)

[akarnokd]

I don't know, do you want the next's value replace the first's value?

[JakeWharton]

There is no first value because the method is on Completable. It's essentially a flatMap.

[akarnokd]

Right, didn't connect Completable. I don't see any problem with such an overload. PRs are welcome.

I'll probably give it a go this weekend if no-one else has started.

[stevegury]

Sounds good, glad to review a PR.

[geralt-encore]

Will implementation be just like:

    public final <T> Single<T> andThen(Single<T> next) {
        requireNonNull(next);
        return next.toObservable().delaySubscription(toObservable()).toSingle();
    }

Or is it a bad practice to use these wrappers internally?

[akarnokd]

If you took the time and implement this operator directly, that would be great.

[akarnokd]

Closing via #3799