class InterfaceManager extends ListenerRegistry<InterfaceEvent, InterfaceListener> implements InterfaceService, InterfaceAdminService {

    @Override
    public Set<Interface> getInterfacesByPort(ConnectPoint port) {
        Set<Interface> intfs = interfaces.get(port);
        if (intfs == null) {
            return Collections.emptySet();
        }
        return ImmutableSet.copyOf(intfs);
    }

}