Interface to designate interceptors.

Invoked methods are identified by using the MessageInterceptor annotation. An interceptor method accepts one parameter of a certain type depending on the message exchange pattern and message direction:

• a RequestResponseObject in case of an input-output pattern on the outgoing direction.
• a RequestObject in case of an input-output pattern or input pattern on the incoming direction.
• a NotificationObject in case of an output pattern in the outgoing direction

An interceptor may throw RuntimeException which are then wrapped as InterceptorException and presented to the user. In order to trace the interceptor exceptions, interceptors should provide a meaningful toString() override.