Github user StefanRRichter commented on the issue:
https://github.com/apache/flink/pull/4851
Also from our offline discussion, I would suggest that this behaves as: if
an operator with a given ID participated in a checkpoint, it should be marked
as restored. From this definition, all cases should be derived. I believe this
is slightly different to the current implementation. Both make sense, so I
think we should agree to something. @pnowojski @aljoscha which is the better
definition for you?---
