Github user patricker commented on the issue:
https://github.com/apache/nifi/pull/3068
I like your #2 approach, as shown in this PR. I haven't tested it yet, but
can you provide a better description on the property? Right now there is no way
for a user to know that TAR is the expected merge format (instead of, for
example, the NiFi FlowFile packing format)---
