Retrieve peer router MAC address using ARP.

Change-Id: I494902d28779288219f631f91080596c7b1ea1fa
(cherry picked from commit 542052721ead4f2b74d954a6328d9de0184d9f65)
diff --git a/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/impl/DistributedKubevirtRouterStore.java b/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/impl/DistributedKubevirtRouterStore.java
index 8f3fdbd..87de35e 100644
--- a/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/impl/DistributedKubevirtRouterStore.java
+++ b/apps/kubevirt-networking/app/src/main/java/org/onosproject/kubevirtnetworking/impl/DistributedKubevirtRouterStore.java
@@ -270,7 +270,8 @@
                             notifyDelegate(new KubevirtRouterEvent(
                             KUBEVIRT_ROUTER_EXTERNAL_NETWORK_ATTACHED,
                             router, entry.getKey(), entry.getValue(),
-                            newValue.peerRouter().ipAddress().toString())));
+                            newValue.peerRouter().ipAddress().toString(),
+                                    newValue.peerRouter().macAddress())));
             }
 
             if (oldValue.external().size() > 0 && newValue.external().size() == 0) {
@@ -279,7 +280,8 @@
                             notifyDelegate(new KubevirtRouterEvent(
                             KUBEVIRT_ROUTER_EXTERNAL_NETWORK_DETACHED,
                             router, entry.getKey(), entry.getValue(),
-                            oldValue.peerRouter().ipAddress().toString())));
+                            oldValue.peerRouter().ipAddress().toString(),
+                                    oldValue.peerRouter().macAddress())));
             }
 
             Set<String> added = new HashSet<>(newValue.internal());