Invoked to handle a non-null event handler method result. The handler should determine whether the value is
acceptable, and throw an exception if not. Any thrown exception will be wrapped to identify the component and
method from which the value was returned.
Boolean values are not passed to the callback. Booleans are used to indicate that the event has been
handled (true, meaning the event is handled and aborted) or that a further search for handlers should continue
(false, meaning the event was not handled, is not aborted, and the search up the component hierarchy for event
handler methods should continue). If a component event method returns true, then
Event.isAborted() will return true.
result - the result value returned from the event handler method
true if the event is aborted, false if the event may continue