[ONOS-7752] check north-south reachability for troubleshoot purpose

Change-Id: I973047c0fcd4fb241ad010fbbef9d016510b8deb
diff --git a/apps/openstacknetworking/app/src/test/java/org/onosproject/openstacknetworking/impl/InstancePortServiceAdapter.java b/apps/openstacknetworking/app/src/test/java/org/onosproject/openstacknetworking/impl/InstancePortServiceAdapter.java
index 885c7d8..b0efdfa 100644
--- a/apps/openstacknetworking/app/src/test/java/org/onosproject/openstacknetworking/impl/InstancePortServiceAdapter.java
+++ b/apps/openstacknetworking/app/src/test/java/org/onosproject/openstacknetworking/impl/InstancePortServiceAdapter.java
@@ -54,6 +54,11 @@
     }
 
     @Override
+    public IpAddress floatingIp(String osPortId) {
+        return null;
+    }
+
+    @Override
     public void addListener(InstancePortListener listener) {
 
     }