RxJava3DiffSince0421

https://github.com/ReactiveX/RxJava/pull/5449
Remove the @NonNull annotation from Function

https://github.com/ReactiveX/RxJava/pull/5447
Remove @NonNull annotation in Consumer method parameter

https://github.com/ReactiveX/RxJava/pull/5444
2x: Fix wording in Async and Publish processors javadoc.

https://github.com/ReactiveX/RxJava/pull/5441
2.x: fix periodic scheduler purging config not honored

https://github.com/ReactiveX/RxJava/pull/5440
2.x: concat to report isDisposed consistently with termination

https://github.com/ReactiveX/RxJava/pull/5436
2.x: Gradle to use less memory, missed an export command

https://github.com/ReactiveX/RxJava/pull/5434
2.x: fix time bounded replaySubject getValue() inconsistency with getValues() on old items

https://github.com/ReactiveX/RxJava/pull/5432
2.x: fix/clarify the Observable class' javadoc

https://github.com/ReactiveX/RxJava/pull/5427
2.x: fix buffer(time, maxSize) duplicating buffers on time-size race

https://github.com/ReactiveX/RxJava/pull/5422
2.x: more eager cancellation in flatMapX

https://github.com/ReactiveX/RxJava/pull/5421
2.x: attempt to fix a few time-sensitive tests.

https://github.com/ReactiveX/RxJava/pull/5419
2.x: fix periodic scheduling with negative period causing IAE

https://github.com/ReactiveX/RxJava/pull/5415
2.x: fix doOnNext failure not triggering doOnError when fused

https://github.com/ReactiveX/RxJava/commit/84d333e07459d8a786f8a549c0b1f4cd69a8f532
2.x: Fix a small typo in Single.delay

https://github.com/ReactiveX/RxJava/commit/4d8f008cb6823730b5e25fea559905a811d8ce32
2.x: add missing 'the' to the changed sentences of 5413

https://github.com/ReactiveX/RxJava/pull/5413
2.x: Add empty source clauses to javadocs of combineLatest operators

https://github.com/ReactiveX/RxJava/pull/5409
Corrected Single.delay documentation

https://github.com/ReactiveX/RxJava/pull/5406
Fix javadoc for Observable.reduce() and Observable.reduceWith()

https://github.com/ReactiveX/RxJava/pull/5407
DefaultSubscriber javadoc sample fix

https://github.com/ReactiveX/RxJava/pull/5405
DefaultObserver javadoc example fix

https://github.com/ReactiveX/RxJava/pull/5403
2.x: Fix documentation of Single.doAfterTerminate.

https://github.com/ReactiveX/RxJava/pull/5386
2.x: add subscribeOn overload to avoid same-pool deadlock with create

https://github.com/ReactiveX/RxJava/pull/5391
Changed minimum value of rx2.buffer-size to 1

https://github.com/ReactiveX/RxJava/pull/5379
2.x: add missing null checks on values returned by user functions

https://github.com/ReactiveX/RxJava/pull/5383
Fixed Javadoc for SingleFlatMapIterableObservable. (already fixed from an earlier commit)

https://github.com/ReactiveX/RxJava/pull/5378
2.x: make SingleMap not allow map function return null

https://github.com/ReactiveX/RxJava/pull/5367
2.x: make sure interval+trampoline can be stopped

https://github.com/ReactiveX/RxJava/commit/0b0355e3bc09326c8005fd26d09e7c1eb4aeb6e3
2.x: Replace Action1 with Consumer in docs

https://github.com/ReactiveX/RxJava/pull/5354
2.x: Fix typo in error message.

https://github.com/ReactiveX/RxJava/pull/5351
2.x: update some marbles of Observable

https://github.com/ReactiveX/RxJava/pull/5347
2.x: Fix Javadoc of FunctionX

https://github.com/ReactiveX/RxJava/pull/5344
2.x: add tryOnError to create/XEmitter API

https://github.com/ReactiveX/RxJava/pull/5343
Fix Javadoc for Maybe.toSingle

https://github.com/ReactiveX/RxJava/pull/5324
Mark VolatileSizeArrayList as RandomAccess list

https://github.com/ReactiveX/RxJava/pull/5310
2.x: Apply promotions for v2.1

https://github.com/ReactiveX/RxJava/pull/5309
2.x: Fix Javadoc of Flowable.toObservable 

https://github.com/ReactiveX/RxJava/pull/5307
2.x: Apply promotions for v2.1