Given that the attachment we send to the JDK SctpChannel is always null, ignore any attachment that is sent back to our NotificationHandler attachment and just pass through the Notification itself.  This allows us to get rid of the SctpNotificationEvent and reduce our object creation overhead
Use the RecvByteBufAllocator rather than the receive buffer size to reduce empty buffers and to allow user-specified buffers rather than always creating a direct buffer