This differs from DelegatingIntroductionInterceptor in that a single
instance of this class can be used to advise multiple target objects, and each target
object will have its own delegate (whereas DelegatingIntroductionInterceptor
shares the same delegate, and hence the same state across all targets).
The suppressInterface method can be used to suppress interfaces
implemented by the delegate class but which should not be introduced to the
owning AOP proxy.
An instance of this class is serializable if the delegates are.
Note: There are some implementation similarities between this class and
DelegatingIntroductionInterceptor that suggest a possible refactoring
to extract a common ancestor class in the future.
Subclasses may need to override this if they want to perform custom
behaviour in around advice. However, subclasses should invoke this
method, which handles introduced interfaces and forwarding to the target.
Proceed with the supplied MethodInterceptor.
Subclasses can override this method to intercept method invocations on the
target object which is useful when an introduction needs to monitor the object
that it is introduced into. This method is never called for
MethodInvocations on the introduced interfaces.