Github user MikeThomsen commented on the issue:
https://github.com/apache/nifi/pull/2259
Thanks!
1. We can't because "$" is an illegal starting character in Avro. That's
why I was grumbling about "$date" operations on the mailing list. Fortunately,
for simple puts there is a good work around.
2. Yeah, we could. I think that would need to support EL too.---
