Fix: to register eventlisteners for virtualnetwork

Changes.
1. Virtual network service inherite listener service

Change-Id: Ie2911916b2912e3c8cbd2069e9563e1f5e2c837f
diff --git a/incubator/api/src/main/java/org/onosproject/incubator/net/virtual/VirtualNetworkService.java b/incubator/api/src/main/java/org/onosproject/incubator/net/virtual/VirtualNetworkService.java
index 21f721c..07775dd 100644
--- a/incubator/api/src/main/java/org/onosproject/incubator/net/virtual/VirtualNetworkService.java
+++ b/incubator/api/src/main/java/org/onosproject/incubator/net/virtual/VirtualNetworkService.java
@@ -18,6 +18,7 @@
 import com.google.common.annotations.Beta;
 import org.onlab.osgi.ServiceDirectory;
 import org.onosproject.core.ApplicationId;
+import org.onosproject.event.ListenerService;
 import org.onosproject.net.DeviceId;
 
 import java.util.Set;
@@ -26,7 +27,8 @@
  * Service for querying virtual network inventory.
  */
 @Beta
-public interface VirtualNetworkService {
+public interface VirtualNetworkService
+        extends ListenerService<VirtualNetworkEvent, VirtualNetworkListener> {
 
     /**
      * The topic used for obtaining globally unique ids.
diff --git a/incubator/api/src/test/java/org/onosproject/incubator/net/virtual/event/AbstractVirtualListenerManagerTest.java b/incubator/api/src/test/java/org/onosproject/incubator/net/virtual/event/AbstractVirtualListenerManagerTest.java
index 1195e69..23934b5 100644
--- a/incubator/api/src/test/java/org/onosproject/incubator/net/virtual/event/AbstractVirtualListenerManagerTest.java
+++ b/incubator/api/src/test/java/org/onosproject/incubator/net/virtual/event/AbstractVirtualListenerManagerTest.java
@@ -34,6 +34,7 @@
 import org.onosproject.incubator.net.virtual.VirtualHost;
 import org.onosproject.incubator.net.virtual.VirtualLink;
 import org.onosproject.incubator.net.virtual.VirtualNetwork;
+import org.onosproject.incubator.net.virtual.VirtualNetworkListener;
 import org.onosproject.incubator.net.virtual.VirtualNetworkService;
 import org.onosproject.incubator.net.virtual.VirtualPort;
 import org.onosproject.net.DeviceId;
@@ -301,6 +302,16 @@
         public ApplicationId getVirtualNetworkApplicationId(NetworkId networkId) {
             return null;
         }
+
+        @Override
+        public void addListener(VirtualNetworkListener listener) {
+
+        }
+
+        @Override
+        public void removeListener(VirtualNetworkListener listener) {
+
+        }
     }
 
     private  class TestServiceDirectory implements ServiceDirectory {
diff --git a/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/provider/DefaultVirtualFlowRuleProviderTest.java b/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/provider/DefaultVirtualFlowRuleProviderTest.java
index d8ae05d..0d3c8cc 100644
--- a/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/provider/DefaultVirtualFlowRuleProviderTest.java
+++ b/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/provider/DefaultVirtualFlowRuleProviderTest.java
@@ -39,6 +39,7 @@
 import org.onosproject.incubator.net.virtual.VirtualLink;
 import org.onosproject.incubator.net.virtual.VirtualNetwork;
 import org.onosproject.incubator.net.virtual.VirtualNetworkAdminService;
+import org.onosproject.incubator.net.virtual.VirtualNetworkListener;
 import org.onosproject.incubator.net.virtual.VirtualPort;
 import org.onosproject.net.ConnectPoint;
 import org.onosproject.net.DefaultAnnotations;
@@ -452,6 +453,16 @@
                                       PortNumber portNumber) {
 
         }
+
+        @Override
+        public void addListener(VirtualNetworkListener listener) {
+
+        }
+
+        @Override
+        public void removeListener(VirtualNetworkListener listener) {
+
+        }
     }
 
     private static class TestTopologyService extends TopologyServiceAdapter {
diff --git a/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/provider/DefaultVirtualPacketProviderTest.java b/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/provider/DefaultVirtualPacketProviderTest.java
index 675feac..dc99153 100644
--- a/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/provider/DefaultVirtualPacketProviderTest.java
+++ b/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/provider/DefaultVirtualPacketProviderTest.java
@@ -38,6 +38,7 @@
 import org.onosproject.incubator.net.virtual.VirtualLink;
 import org.onosproject.incubator.net.virtual.VirtualNetwork;
 import org.onosproject.incubator.net.virtual.VirtualNetworkAdminService;
+import org.onosproject.incubator.net.virtual.VirtualNetworkListener;
 import org.onosproject.incubator.net.virtual.VirtualPort;
 import org.onosproject.incubator.net.virtual.provider.AbstractVirtualProviderService;
 import org.onosproject.incubator.net.virtual.provider.VirtualPacketProvider;
@@ -381,6 +382,16 @@
                                       PortNumber portNumber) {
 
         }
+
+        @Override
+        public void addListener(VirtualNetworkListener listener) {
+
+        }
+
+        @Override
+        public void removeListener(VirtualNetworkListener listener) {
+
+        }
     }
 
     private static class TestVirtualPacketProviderService