Listener for resource change events.
ResourceChangeListener objects are registered with the Framework service
registry and are notified with
ResourceChange objects when a
change occurs.
ResourceChangeListener objects can inspect the received
ResourceChange objects to
determine the type of change, location and other properties.
ResourceChangeListener objects must be registered with a service property
ResourceChangeListener#PATHS whose value is the list of resource paths for which
the listener is interested in getting change events.
By default a resource listener gets only local events which means events
caused by changes persisted on the same instance as this listener is registered.
If the resource listener is interested in external events, the implementation
should implement the
ExternalResourceChangeListener interface, but still register
the service as a
ResourceChangeListener service.