Converted UiSharedTopologyModel to be a @Service.

Change-Id: Idc8df1b9c0a52db01ac545567dacc0e1c770f84a
diff --git a/core/api/src/main/java/org/onosproject/net/region/RegionService.java b/core/api/src/main/java/org/onosproject/net/region/RegionService.java
index 7591e72..259c8b0 100644
--- a/core/api/src/main/java/org/onosproject/net/region/RegionService.java
+++ b/core/api/src/main/java/org/onosproject/net/region/RegionService.java
@@ -16,6 +16,7 @@
 
 package org.onosproject.net.region;
 
+import org.onosproject.event.ListenerService;
 import org.onosproject.net.DeviceId;
 
 import java.util.Set;
@@ -23,7 +24,7 @@
 /**
  * Service for interacting with inventory of network control regions.
  */
-public interface RegionService {
+public interface RegionService extends ListenerService<RegionEvent, RegionListener> {
 
     /**
      * Returns set of all regions.