exception
Determines which ExceptionSignatureKind, if any, the receiver method conforms to.
A method annotated with @ExceptionHandler is only considered valid if it matches one of the expected shapes:
(event: Event)→ EVENT_ONLY(throwable: Throwable)→ THROWABLE_ONLY(event: Event, throwable: Throwable)→ EVENT_AND_THROWABLE
Parameter matching is polymorphic: a parameter typed as a supertype of the actual event or exception (e.g. Event, Throwable, Exception) is still considered compatible.
Receiver
the reflective Method being inspected.
Return
the recognized signature kind, or null if the method does not match any supported exception-handler shape.