Adding ability to wipe-out UI model cache and network config.

Change-Id: I3d4aecb989c1d4fc2589471fa3ddd53f62c49eb5
diff --git a/core/api/src/main/java/org/onosproject/ui/UiExtensionService.java b/core/api/src/main/java/org/onosproject/ui/UiExtensionService.java
index 3794af2..4764412 100644
--- a/core/api/src/main/java/org/onosproject/ui/UiExtensionService.java
+++ b/core/api/src/main/java/org/onosproject/ui/UiExtensionService.java
@@ -59,4 +59,9 @@
      * @return the navigation localization bundle
      */
     LionBundle getNavLionBundle();
+
+    /**
+     * Refreshes the backing model.
+     */
+    void refreshModel();
 }
diff --git a/core/api/src/test/java/org/onosproject/ui/UiExtensionServiceAdapter.java b/core/api/src/test/java/org/onosproject/ui/UiExtensionServiceAdapter.java
index 8a246dc..93bcf9f 100644
--- a/core/api/src/test/java/org/onosproject/ui/UiExtensionServiceAdapter.java
+++ b/core/api/src/test/java/org/onosproject/ui/UiExtensionServiceAdapter.java
@@ -45,4 +45,8 @@
     public LionBundle getNavLionBundle() {
         return null;
     }
+
+    @Override
+    public void refreshModel() {
+    }
 }