Github user pnowojski commented on the issue:
https://github.com/apache/flink/pull/6071
@zentol as @NicoK suggested I have missed netty 4.1 upgrade without credit
base flow control. It turns out that this upgrade is unstable without this fix:
https://github.com/apache/flink/pull/5571, so we should merge it before this
one.---
