Github user dawidwys commented on the issue:
https://github.com/apache/flink/pull/5649
I am not sure about the value of those changes. The keying and the
`KeyedProcessFunction`s are applied onto `DataStream` plus tests in
`DataStreamTest` cover checks if the resulting stream is keyed e.g.
DataStreamTest.java:328. I seems then it is the right place for the tests you
moved, at least for me.
Therefore I would be against introducing this change at all.---
