Great, finally reliable subroutine attributes!
Some things you have to look-out for which are still unfixed in the latest version (I have not reported these as bugs anymore as the author now also recommends another module):
As the author said: For true JSON encoding you should probably better use JSON::XS. I, by the way, wildly appreciate that the author recommends a better module - I first found JSON::XS through the hint in the documentation here.
We've since switched to this module - if you ever need JSON encoding/decoding - use this!