Returns true if Activity is a valid source for transition.
This depends of activitie's type property, it can accept to be a
source for transition if it is a normal or starting.
Returns true if Activity is a valid target for transition.
This depends of activitie's type property, it can accept to be a
target for for transition if it is a normal or ending.
Create a clone of the cell. The cloning of the
user object is deferred to the cloneUserObject()
method.
NOTE: this original method of DefaultGraphCell is
modified to retain synchronization of userObject and
value attribute from attribute map when model
is attribute store
Object a clone of this object.