Github user pnowojski commented on the issue:
https://github.com/apache/flink/pull/4777
@aljoscha `combine.self="override"` couldn't work because `<rules>` can not
be empty, so I couldn't override `maven-enforcer-plugin` with an empty
configuration. Instead I have enabled convergence by default in parent pom and
configure it `<skip>true</skip>` in modules that are not fixed yet.---
