Deprecated white board service that represents a listener for endpoints.
 
 An Endpoint Listener represents a participant in the distributed model that
 is interested in Endpoint Descriptions.
 
 The Endpoint Listener is called back when matching endpoints are added or
 removed. Consumers interested in the modification of endpoints, when
 associated service properties are changed, should use an
 
EndpointEventListener instead.
 
 This white board service can be used in many different scenarios. However,
 the primary use case is to allow a remote manager to be informed of Endpoint
 Descriptions available in the network and inform the network about available
 Endpoint Descriptions.
 
 Both the network bundle and the manager bundle register an Endpoint Listener
 service. The manager informs the network bundle about Endpoints that it
 creates. The network bundles then uses a protocol like SLP to announce these
 local end-points to the network.
 
 If the network bundle discovers a new Endpoint through its discovery
 protocol, then it sends an Endpoint Description to all the Endpoint Listener
 services that are registered (except its own) that have specified an interest
 in that endpoint.
 
 Endpoint Listener services can express their 
scope with the service
 property 
ENDPOINT_LISTENER_SCOPE. This service property is a list of
 filters. An Endpoint Description should only be given to a Endpoint Listener
 when there is at least one filter that matches the Endpoint Description
 properties.
 
 This filter model is quite flexible. For example, a discovery bundle is only
 interested in locally originating Endpoint Descriptions. The following filter
 ensure that it only sees local endpoints.
 
 
   (org.osgi.framework.uuid=72dc5fd9-5f8f-4f8f-9821-9ebb433a5b72)
 
 
 In the same vein, a manager that is only interested in remote Endpoint
 Descriptions can use a filter like:
 
 
   (!(org.osgi.framework.uuid=72dc5fd9-5f8f-4f8f-9821-9ebb433a5b72))
 
 
 Where in both cases, the given UUID is the UUID of the local framework that
 can be found in the Framework properties.
 
 The Endpoint Listener's scope maps very well to the service hooks. A manager
 can just register all filters found from the Listener Hook as its scope. This
 will automatically provide it with all known endpoints that match the given
 scope, without having to inspect the filter string.
 
 In general, when an Endpoint Description is discovered, it should be
 dispatched to all registered Endpoint Listener services. If a new Endpoint
 Listener is registered, it should be informed about all currently known
 Endpoints that match its scope. If a getter of the Endpoint Listener service
 is unregistered, then all its registered Endpoint Description objects must be
 removed.
 
 The Endpoint Listener models a 
best effort approach. Participating
 bundles should do their utmost to keep the listeners up to date, but
 implementers should realize that many endpoints come through unreliable
 discovery processes.