Github user walterddr commented on the issue:
https://github.com/apache/flink/pull/5555
Thanks @fhueske, I had the exact same feeling. Just attaching `MapState`
towards the back of the `Row` might be a current working solution for now, but
will probably be nasty to maintain in the future.
I am planning to go ahead and create an optimization ticket further down
once I had FLINK-8690 completed. What do you think?---
