imapsieve environment variables missing?

[MRob]

RFC6785 says imap.user and imap.email environment variables should be 
made available but I can't access them no matter what I try. Are they 
not implemented because vnd.dovecot.environment already provides the 
username? (which does work for me)

If imap.user and imap.email are there, can you provide an example how to 
access them so I can see what I did wrong?