Github user joewitt commented on the issue:
https://github.com/apache/nifi/pull/2176
@peter-gergely-horvath I've seen RAT complaints on files that are no longer
part of the actual source repository. I run 'git clean -fxd' to get to a very
clean/repo intended state but this can remove temp files and things folks need
for their IDE. Could you please verify this is happening on a fresh/updated
repo and that these aren't just files that were lying after rebases/etc..---
