Github user zenfenan commented on the issue:
https://github.com/apache/nifi/pull/2585
@sbouchex The project has checkstyle configuration which is checked/enabled
when you build with the `contrib-check` Maven profile. The nifi-grpc-processors
has some problem in getting built with the complete project. You can do this
first `mvn clean -Pinclude-grpc` and then run `mvn
-Pcontrib-check install`---
