public void removeListener( @Nonnull JID entity, @Nonnull EntityCapabilitiesListener listener ) {
        userSpecificCapabilitiesListener.remove( entity, listener );
    }
Removes a previously registered event listener for a particular entity, if such a combination is currently
registered.

@param entity The entity for which the listener was registered.
@param listener The event listener to be removed.
xmppserver/src/main/java/org/jivesoftware/openfire/entitycaps/EntityCapabilitiesManager.java