abstract fun afterMessageHandled(message: Message<*>, channel: MessageChannel, handler: MessageHandler, @Nullable ex: Exception): Unit
Invoked inside the Runnable submitted to the Executor after calling the target MessageHandler regardless of the outcome (i.e. Exception raised or not) thus allowing for proper resource cleanup.
Note that this will be invoked only if beforeHandle successfully completed and returned a Message, i.e. it did not return null.
channel - the channel on which the message was sent to