Github user mattyb149 commented on the issue:
https://github.com/apache/nifi/pull/2113
Makes sense to me, we had to do the same with Elasticsearch 2.x and 5.x
because of the difference in transport client versions. As folks move
exclusively to ES5+, it would be nice to deprecate the other NARs and go
forward with versions of all the processors (Get,Put,Search, etc.) using the
new Java client.---
