In the "JMX Instrumentation and Agent Specification, v1.0"
(Dec.99, public release 2),
in the specification of the removeNotificationListener method of the NotificationBraodcaster interface (chapter 2, p48),
it is specified that this method can optionally take as second parameter a handback object: if it is provided only the entry corresponding to the (listener, handback) pair should be removed otherwise all entries for the listener are removed.

However, in the current Reference Implementation of this specification, the removeNotificationListener method of the NotificationBroadcaster interface takes only ONE parameter, which is the listener to be removed (therefore, all entries for this listener are always removed) .