When addNotificationListener is called for the first time
to add a listener to an existing NotificationBroadcaster
MBean from a remote client, then the client performs an
internal addNotificationListener on the MBeanServerDelegate
to be able to do some cleanup on MBean deletion.

In order to keep symmetry after removing the latest user
defined notification listener the client should internally
call removeNotificationListener on the MBeanServerDelegate
but it is not the case in the current implementation.

The question that arises here is how do we make the difference
between the user calling addNotificationListener on the MBSD
and the connector client code invoking the same call internally?