1.x: Add Completable.doOnCompleted and deprecate Completable.doOnComplete

[zach-klippenstein]

Closes #3700.

[akarnokd]

Wait, what? I thought you wanted to add Completable.doOnCompleted(). I see no reason to change the established naming of Observable.doOnCompleted(). In fact, for consistency, I'd rather prefer adding Completable.doOnCompleted.

[zach-klippenstein]

That makes sense. The only reason I did it this way is because on the 2.x branch both Observable and Completable use doOnComplete().

[akarnokd]

Yes, those follow the reactive-streams convention and Completable started out as a 2.x addition. In the meantime, I'll fix that test failure.

[zach-klippenstein]

Changed Completable instead, updated tests to match.

[akarnokd]

👍

[zsxwing]

@zach-klippenstein Thanks! Just updated the title. 👍

[stevegury]

👍