ONOS-6258: UiTopo2Overlay et al.
- Added Topo2TrafficMessageHandler
- Wired topo2 traffic overlay into topo2 view

Change-Id: I2b67af6abc10f737b8d3183d219d8c651bf57e31
diff --git a/web/gui/src/main/java/org/onosproject/ui/impl/UiWebSocket.java b/web/gui/src/main/java/org/onosproject/ui/impl/UiWebSocket.java
index c302c6b..2179f42 100644
--- a/web/gui/src/main/java/org/onosproject/ui/impl/UiWebSocket.java
+++ b/web/gui/src/main/java/org/onosproject/ui/impl/UiWebSocket.java
@@ -296,6 +296,10 @@
             overlayCache.destroy();
             overlayCache = null;
         }
+        if (overlay2Cache != null) {
+            overlay2Cache.destroy();
+            overlay2Cache = null;
+        }
     }
 
     // Sends initial information (username and cluster member information)