/**
  * Get the network by the given fabric ID. Return null if not found.
  *
  * @param networks
  * @param fabricId
  * @return
  */
 private Network getNetworkByNativeId(List<Network> networks, String fabricId) {
   for (Network network : networks) {
     if (network != null
         && network.getNativeId() != null
         && network.getNativeId().equals(fabricId)) {
       return network;
     }
   }
   return null;
 }
 /**
  * Get the connected network systems which are connected by the given transit network.
  *
  * @param transitNetwork
  * @param allNetworks
  * @return
  */
 private Set<String> getConnectedNetworkSystems(String transitNetwork, List<Network> allNetworks) {
   Set<String> connectedNetworkSystems = new HashSet<String>();
   for (Network network : allNetworks) {
     if (network.getNetworkSystems() != null && transitNetwork.equals(network.getNativeId())) {
       for (String networkSystem : network.getNetworkSystems()) {
         connectedNetworkSystems.add(networkSystem);
       }
     }
   }
   return connectedNetworkSystems;
 }