4.x: Cleanup anyonymous inner class uses in unit tests #8080
Description
They are the remnant of the Java 6 era of RxJava.
We didn't want to touch them for fear of breakage.
They are increasingly old and increasingly difficult to look at and see what they are doing due to the boilerplate surrounding them.
Thus we welcome cleanups for such tests. Please do it in small chunks so the tests are not broken or disappear.