ONOS-4075 - Distributed virtual network store implementation,
and virtual network manager Junit tests.

Change-Id: Ic1f82822c894e3c394aa95df1e76ae59fe218120
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 01681ef..c83b2c5 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
@@ -27,6 +27,11 @@
 public interface VirtualNetworkService {
 
     /**
+     * The topic used for obtaining globally unique ids.
+     */
+    String VIRTUAL_NETWORK_TOPIC = "virtual-network-ids";
+
+    /**
      * Returns a collection of all virtual networks created on behalf of the
      * specified tenant.
      *