Github user joewitt commented on the issue:
https://github.com/apache/nifi/pull/2882
am building against master - is 1.9.0. changing it to 1.9.0-SNAPSHOT and
ignoring last commit addresses it. travis fails for a similar reason i'd
guess. Probably makes sense to ditch the merge commits, squash, rebase to
latest. But in any case is building now i think---
