Implement event notification of resource event

When a resource is registered or unregistered, a resource event is notified

Change-Id: I40e66761966ef2126366424a14bb3193fc850e5a
diff --git a/core/api/src/main/java/org/onosproject/net/newresource/ResourceService.java b/core/api/src/main/java/org/onosproject/net/newresource/ResourceService.java
index ad684c8..966de50 100644
--- a/core/api/src/main/java/org/onosproject/net/newresource/ResourceService.java
+++ b/core/api/src/main/java/org/onosproject/net/newresource/ResourceService.java
@@ -17,6 +17,7 @@
 
 import com.google.common.annotations.Beta;
 import com.google.common.collect.ImmutableList;
+import org.onosproject.event.ListenerService;
 
 import java.util.Arrays;
 import java.util.Collection;
@@ -29,7 +30,7 @@
  * Service for allocating/releasing resource(s) and retrieving allocation(s) and availability.
  */
 @Beta
-public interface ResourceService {
+public interface ResourceService extends ListenerService<ResourceEvent, ResourceListener> {
     /**
      * Allocates the specified resource to the specified user.
      *