When first selecting “Enable sharing group in rosters” it doesnt select any “Show group…” option below automaticly. So after pressing Save Settings button you get “pretty” Jetty error:) I think it should yell to admin about selecting some of these options, or it should select first one by default.
Thanks for the bug report. I filed the issue JM-229 for this problem. I’'ll let you know when the problem has been fixed.