CORD Subscriber GUI - Added a little logging.

Change-Id: I96f674008cd8e6b3d7b3f517444a5ef9fd8b761c
diff --git a/apps/demo/cord-gui/src/main/java/org/onosproject/cord/gui/model/UrlFilterFunction.java b/apps/demo/cord-gui/src/main/java/org/onosproject/cord/gui/model/UrlFilterFunction.java
index 0c06b10..e26935d 100644
--- a/apps/demo/cord-gui/src/main/java/org/onosproject/cord/gui/model/UrlFilterFunction.java
+++ b/apps/demo/cord-gui/src/main/java/org/onosproject/cord/gui/model/UrlFilterFunction.java
@@ -27,6 +27,7 @@
 public class UrlFilterFunction extends DefaultXosFunction {
 
     private static final String LEVEL = "level";
+    private static final String URI_PATTERN = "%s/%s/";
 
     /**
      * Denotes the URL filtering levels available. From most restrictive
@@ -87,6 +88,6 @@
     public String xosUrlApply(SubscriberUser user) {
         XosFunctionDescriptor xfd = XosFunctionDescriptor.URL_FILTER;
         UrlFilterMemento memo = (UrlFilterMemento) user.getMemento(xfd);
-        return xfd.id() + "/" + memo.level();
+        return String.format(URI_PATTERN, xfd.id(), memo.level());
     }
 }