overrid updat layout uml chang event event contain equal event properti concurr equal event properti updat layout event event properti concurr region incom outgo transit incom outgo transit redirect concurr composit state contain todo comparison suspect us equal method code block fact execut hesit chang trigger code us awar problem usag introduc think need abl differ wai implement intent correct edg draw actual allow bob incom outgo object owner owner collect transact collect event valu transact object transit transact iter incom model facad transit transit model common behavior helper set target transit model facad contain owner model facad transit transit model state machin helper set sourc transit model facad contain owner 