2.2.9 release preparations

[akarnokd]

Version 2.2.9 - May 30, 2019 (Maven)

Bugfixes

• Pull 6488: Fix zip not stopping the subscription upon eager error.

Documentation changes

• Pull 6453: Fixed wrong type referenced in Maybe and Single JavaDocs.
• Pull 6458: Update the Javadoc of the retry operator.

Other

• Pull 6452: Remove dependency of Schedulers from ObservableRefCount.
• Pull 6461: Change error message in ObservableFromArray.
• Pull 6469: Remove redundant methods from sample(Observable).
• Pull 6470: Remove unused import from Flowable.java.
• Pull 6485: Remove unused else from the Observable.

[akarnokd]

Moved the release a week from now so that we may include the upgrade of Reactive Streams 1.0.3 due soon.

[akarnokd]

Closing via v2.2.9.