private void initialize(final DataBroker dataBroker) {
   Preconditions.checkNotNull(dataBroker);
   listenerRegistration =
       dataBroker.registerDataChangeListener(
           LogicalDatastoreType.OPERATIONAL, NETCONF_DEVICE_PATH, this, DataChangeScope.SUBTREE);
   LOG.info("NetconfEventSourceManager initialized.");
 }
 public void start() {
   InstanceIdentifier<Node> path =
       InstanceIdentifier.create(NetworkTopology.class)
           .child(Topology.class, new TopologyKey(MdsalHelper.OVSDB_TOPOLOGY_ID))
           .child(Node.class);
   registration =
       dataBroker.registerDataChangeListener(
           LogicalDatastoreType.OPERATIONAL, path, this, DataChangeScope.SUBTREE);
   LOG.info(
       "netvirt OvsdbDataChangeListener: dataBroker= {}, registration= {}",
       dataBroker,
       registration);
   triggerUpdates();
 }