Github user StephanEwen commented on the issue:
https://github.com/apache/flink/pull/5356
I am wondering whether this discussion is a bit confused.
All state facing the user in the APIs already has the behavior that there
is no `null`, but only empty iterators. That's because all state is wrapped
into a `UserFacingListState` in the `DefaultKeyedStateStore`.
So, is this a non-issue, actually? Something that may only affect test
implementations of `ListState`---
