Fix: resolve a NPE caused by null peer-router on updating vRouter

Change-Id: I788b9e3c4a3df0ca3d5f0fa3c5e89f1306864e6d
diff --git a/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/impl/KubevirtRouterWatcher.java b/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/impl/KubevirtRouterWatcher.java
index a52eaab..bc87820 100644
--- a/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/impl/KubevirtRouterWatcher.java
+++ b/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/impl/KubevirtRouterWatcher.java
@@ -247,7 +247,7 @@
             KubevirtRouter router = parseKubevirtRouter(resource);
 
             KubevirtPeerRouter oldPeerRouter = adminService.router(router.id()).peerRouter();
-            if (oldPeerRouter != null
+            if (oldPeerRouter != null && router.peerRouter() != null
                     && Objects.equals(oldPeerRouter.ipAddress(), router.peerRouter().ipAddress())
                     && oldPeerRouter.macAddress() != null
                     && router.peerRouter().macAddress() == null) {