OF-1147: Thread safety when modifying admin console
OF-1147: Thread safety when modifying admin console

When there are multiple plugins loading at the same time, they can
concurrently attempt to add models to the admin console. To prevent
concurrency issues, those methods are made synchronous.

akrherz/Openfire,igniterealtime/Openfire,speedy01/Openfire,GregDThomas/Openfire,guusdk/Openfire,igniterealtime/Openfire,igniterealtime/Openfire,speedy01/Openfire,Gugli/Openfire,GregDThomas/Openfire,Gugli/Openfire,Gugli/Openfire,guusdk/Openfire,akrherz/Openfire,akrherz/Openfire,speedy01/Openfire,igniterealtime/Openfire,igniterealtime/Openfire,GregDThomas/Openfire,guusdk/Openfire,speedy01/Openfire,Gugli/Openfire,GregDThomas/Openfire,GregDThomas/Openfire,guusdk/Openfire,guusdk/Openfire,akrherz/Openfire,akrherz/Openfire,Gugli/Openfire,speedy01/Openfire