ReactiveX / RxJava

3.x: Fix Observable.flatMap with maxConcurrency hangs (#6946)
* 3.x: Fix Observable.flatMap with maxConcurrency hangs

* Verify Flowable

Update CHANGES.md

Fix typos in Backpressure.md (#6927)
Fix lower case generic type declaration in reactive pull backpressure's code sample
Fix typo in the Further reading section

Release 2.2.18

More missing version tags

3.x: Add concatEagerDelayError across (#6899)
* 3.x: Add concatEagerDelayError across

* Add more since 3.0.0 tags

3.x: Simplify @return sentences in Flowable JavaDocs (#6847)
* 3.x: Simplify @return sentences in Flowable

* Clear Completable

* Clear Single

* Clean Maybe

* Clean Observable

Release 2.2.17

3.x: [Java 8] Add flattenStreamAsX to Maybe/Single (#6805)
* 3.x: [Java 8] Add flattenStreamAsX to Maybe/Single

* Add RS TCK tests for flattenStreamAsFlowable

Release 2.2.16