There's JID vs String confusion in the webadmin console. From the original report (on the Ignite forum):
(...) I installed Openfire 3.8 (...)
I am facing a issue with Chat Group Service Settings. I created an Chat Group Service. By default Room Creation Permission is Anyone can create a chat room.
But when I to change to Only specific users can create a chat room, --> Save Settings, Then it ask for Allowed Users.
In Add User (JID) what ever I give it gives error.
A fix for this problem was checked in. I've verified that a similar issue does not occur elsewhere.