Github user tillrohrmann commented on the issue:
https://github.com/apache/flink/pull/5112
Thanks for your contribution @bowenli86. I think we should reach first some
kind of consensus on the ML before moving the classes. I'm actually not sure
whether `CollectSink` is something we should keep around since it is not at all
generic and not efficient enough to be seriously used. My gut feeling is that
this is actually a toy sink which should not be part of the `flink-streaming`
modules.---
