Revert "Fix NPE of ProxyArp"

This reverts commit 1b22a2ca4bd2bfad272de93605333c6f80d9448c.

Change-Id: I69500a9315c46785b9b867d49f9e1776cfdf2ea6
diff --git a/apps/proxyarp/src/main/java/org/onosproject/proxyarp/DefaultProxyArp.java b/apps/proxyarp/src/main/java/org/onosproject/proxyarp/DefaultProxyArp.java
index 0f613ac..4f02787 100644
--- a/apps/proxyarp/src/main/java/org/onosproject/proxyarp/DefaultProxyArp.java
+++ b/apps/proxyarp/src/main/java/org/onosproject/proxyarp/DefaultProxyArp.java
@@ -59,7 +59,8 @@
     private ApplicationId appId;
 
     private InternalEdgeListener edgeListener = new InternalEdgeListener();
-    private DefaultNeighbourMessageHandler defaultHandler;
+    private DefaultNeighbourMessageHandler defaultHandler =
+            new DefaultNeighbourMessageHandler(interfaceService);
 
     @Activate
     protected void activate() {
@@ -67,8 +68,6 @@
 
         edgeService.addListener(edgeListener);
         edgeService.getEdgePoints().forEach(this::addDefault);
-
-        defaultHandler = new DefaultNeighbourMessageHandler(interfaceService);
     }
 
     @Deactivate