The root class from which all event state objects shall be derived.
The root class from which all event state objects shall be derived.
All Events are constructed with a reference to the object, the "source",
that is logically deemed to be the object upon which the Event in question
initially occurred upon.
Constructs a prototypical Event.
Parameters: - source - The object on which the Event initially occurred.
Throws: - IllegalArgumentException - if source is null.