2.1.8 release preparations

[akarnokd]

Version 2.1.8 - December 27, 2017 (Maven)

Warning! Behavior change regarding handling illegal calls with null in Processors and Subjects.

The Reactive Streams specification mandates that calling onNext and onError with null should
result in an immediate NullPointerException thrown from these methods. Unfortunately, this requirement was overlooked (it resulted in calls to onError with NullPointerException which meant the Processor/Subject variants entered their terminal state).

If, for some reason, the original behavior is required, one has to call onError with a NullPointerException explicitly:

PublishSubject<Integer> ps = PublishSubject.create();

TestObserver<Integer> to = ps.test();

// ps.onNext(null); // doesn't work anymore

ps.onError(new NullPointerException());

to.assertFailure(NullPointerException.class);

API changes

• Pull 5741: API to get distinct Workers from some Schedulers.
• Pull 5734: Add RxJavaPlugins.unwrapRunnable to help with RxJava-internal wrappers in Schedulers.
• Pull 5753: Add retry(times, predicate) to Single & Completable and verify behavior across them and Maybe.

Documentation changes

• Pull 5746: Improve wording and links in package-infos + remove unused imports.
• Pull 5745: Add/update Observable marbles 11/28.
• Commit 53d5a235: Fix JavaDoc link in observables/package-info.
• Pull 5755: Add marbles for Observable (12/06).
• Pull 5756: Improve autoConnect() JavaDoc + add its marble.
• Pull 5758: Add a couple of @see to Completable.
• Pull 5759: Marble additions and updates (12/11)
• Pull 5773: Improve JavaDoc of retryWhen() operators.
• Pull 5778: Improve BehaviorProcessor JavaDoc.

Bugfixes

• Pull 5747: Fix TrampolineScheduler not calling RxJavaPlugins.onSchedule(), add tests for all schedulers.
• Pull 5748: Check runnable == null in *Scheduler.schedule*().
• Pull 5761: Fix timed exact buffer() calling cancel unnecessarily.
• Pull 5760: Subject/FlowableProcessor NPE fixes, add UnicastProcessor TCK.

Other

• Pull 5771: Upgrade dependency to Reactive Streams 1.0.2
• Pull 5766: Rename XOnSubscribe parameter name to emitter for better IDE auto-completion.