[ONOS-5833] (vCore) Refactor vnet services
to enable event delivery mechanism

Changes
1. Abstact Vnet Listener Manager is added
2. Refactor Vnet services to use it

Change-Id: I178342bfc882c0739f216960358a281903e1385a
diff --git a/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkHostManagerTest.java b/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkHostManagerTest.java
index ca1a314..ed0f3c2 100644
--- a/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkHostManagerTest.java
+++ b/incubator/net/src/test/java/org/onosproject/incubator/net/virtual/impl/VirtualNetworkHostManagerTest.java
@@ -21,6 +21,7 @@
 import org.junit.Before;
 import org.junit.Test;
 import org.onlab.junit.TestUtils;
+import org.onlab.osgi.TestServiceDirectory;
 import org.onosproject.common.event.impl.TestEventDispatcher;
 import org.onosproject.core.CoreService;
 import org.onosproject.incubator.net.virtual.TenantId;
@@ -51,13 +52,14 @@
     private VirtualNetworkManager manager;
     private DistributedVirtualNetworkStore virtualNetworkManagerStore;
     private TestableIntentService intentService = new FakeIntentManager();
+    private TestServiceDirectory testDirectory;
 
     @Before
     public void setUp() throws Exception {
         virtualNetworkManagerStore = new DistributedVirtualNetworkStore();
 
         CoreService coreService = new TestCoreService();
-        virtualNetworkManagerStore.setCoreService(coreService);
+        TestUtils.setField(virtualNetworkManagerStore, "coreService", coreService);
         TestUtils.setField(virtualNetworkManagerStore, "storageService", new TestStorageService());
         virtualNetworkManagerStore.activate();
 
@@ -65,6 +67,10 @@
         manager.store = virtualNetworkManagerStore;
         manager.intentService = intentService;
         NetTestTools.injectEventDispatcher(manager, new TestEventDispatcher());
+
+        testDirectory = new TestServiceDirectory();
+        TestUtils.setField(manager, "serviceDirectory", testDirectory);
+
         manager.activate();
     }