Github user mattyb149 commented on the issue:
https://github.com/apache/nifi/pull/2123
I took the liberty of changing the Lookup Key property to Lookup Value
Field, and updated variables and unit tests and such. +1 LGTM, built and ran
unit tests, also tried a flow with LookupRecord with various settings (Lookup
Value Field set and not set, Insert Entire Record and Insert Record Fields,
etc.). Thank you for the feature! Merging (after rebasing with my addition) to
master---
