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/DefaultVirtualNetwork.java b/incubator/api/src/main/java/org/onosproject/incubator/net/virtual/DefaultVirtualNetwork.java
index c114191..360d385 100644
--- a/incubator/api/src/main/java/org/onosproject/incubator/net/virtual/DefaultVirtualNetwork.java
+++ b/incubator/api/src/main/java/org/onosproject/incubator/net/virtual/DefaultVirtualNetwork.java
@@ -22,7 +22,7 @@
 /**
  * Default implementation of the virtual network descriptor.
  */
-public class DefaultVirtualNetwork implements VirtualNetwork {
+public final class DefaultVirtualNetwork implements VirtualNetwork {
 
     private final NetworkId id;
     private final TenantId tenantId;