[ONOS-3624] update vtnweb's bug and add Not-Null constraints of export.

Change-Id: I7699d8766f0653f5fafd4b32a68051994f43b00e

@@ -413,7 +413,9 @@ public class VTNManager implements VTNService {
         if (type == Objective.Operation.ADD) {
             // Save external port
             Port export = getExPort(device.id());
+            if (export != null) {
                 exPortOfDevice.put(device.id(), export);
+            }
             switchOfLocalHostPorts.put(device.id(), new NetworkOfLocalHostPorts());
         } else if (type == Objective.Operation.REMOVE) {
             exPortOfDevice.remove(device.id());
@@ -777,7 +779,7 @@ public class VTNManager implements VTNService {
         for (RouterInterface r : interfacesSet) {
             // Get all the host of the subnet
             Map<HostId, Host> hosts = hostsOfSubnet.get(r.subnetId());
-            if (hosts.size() > 0) {
+            if (hosts != null && hosts.size() > 0) {
                 subnetVmNum++;
                 if (subnetVmNum >= SUBNET_NUM) {
                     routerInfFlagOfTenant.put(r.tenantId(), true);

@@ -134,6 +134,12 @@ public class RouterInterfaceManager implements RouterInterfaceService {
     @Override
     public boolean addRouterInterface(RouterInterface routerInterface) {
         checkNotNull(routerInterface, ROUTER_INTERFACE_NULL);
+        if (!virtualPortService.exists(routerInterface.portId())) {
+            log.debug("The port ID of interface is not exist whose identifier is {}",
+                      routerInterface.portId().toString());
+            throw new IllegalArgumentException(
+                                               "port ID of interface doesn't exist");
+        }
         verifyRouterInterfaceData(routerInterface);
         routerInterfaceStore.put(routerInterface.subnetId(), routerInterface);
         if (!routerInterfaceStore.containsKey(routerInterface.subnetId())) {
@@ -188,12 +194,6 @@ public class RouterInterfaceManager implements RouterInterfaceService {
             throw new IllegalArgumentException(
                                                "subnet ID of interface doesn't exist");
         }
-        if (!virtualPortService.exists(routerInterface.portId())) {
-            log.debug("The port ID of interface is not exist whose identifier is {}",
-                      routerInterface.portId().toString());
-            throw new IllegalArgumentException(
-                                               "port ID of interface doesn't exist");
-        }
         if (!routerService.exists(routerInterface.routerId())) {
             log.debug("The router ID of interface is not exist whose identifier is {}",
                       routerInterface.routerId().toString());