param node node end drag param old node exist node connect param edg edg drag rerout transit rerout state chang connect node object node object old node object edg prevent chang node old node check paramet type model facad state node model facad state old node model facad transit edg allow transit composit substat vice versa issu object node model facad sourc edg node old node node model facad target edg model facad composit state node model state machin helper sub state node contain node 