CORD-349 Support VLAN cross-connect traffic

Change related to this topic:
- Support VLAN cross-connect traffic
    Utilize ports subjectClass to achieve. For non-xConnect port, set interface VLAN to -1
- Remove VLAN checking since we have multiple VLANs per port
- Hash the L2 interface group key generation to include VLAN as well
- Update the network-cfg.json sample

Other refactoring changes:
- Read next objective stores from srManager directly
- Use constant for flow priority
- CORD-267 Javadoc fix

Change-Id: I4ca8c2d9c8b3633a4a0101c5070d19343f7e5b90
diff --git a/src/main/java/org/onosproject/segmentrouting/PolicyHandler.java b/src/main/java/org/onosproject/segmentrouting/PolicyHandler.java
index 0a4c26d..308d026 100644
--- a/src/main/java/org/onosproject/segmentrouting/PolicyHandler.java
+++ b/src/main/java/org/onosproject/segmentrouting/PolicyHandler.java
@@ -48,18 +48,43 @@
     private FlowObjectiveService flowObjectiveService;
     private TunnelHandler tunnelHandler;
     private final EventuallyConsistentMap<String, Policy> policyStore;
-
+    /**
+     * Result of policy creation.
+     */
     public enum Result {
+        /**
+         * Success.
+         */
         SUCCESS,
+
+        /**
+         * The same policy exists already.
+         */
         POLICY_EXISTS,
+
+        /**
+         * The policy ID exists already.
+         */
         ID_EXISTS,
+
+        /**
+         * Cannot find associated tunnel.
+         */
         TUNNEL_NOT_FOUND,
+
+        /**
+         * Policy was not found.
+         */
         POLICY_NOT_FOUND,
+
+        /**
+         * Policy type {} is not supported yet.
+         */
         UNSUPPORTED_TYPE
     }
 
     /**
-     * Creates a reference.
+     * Constructs policy handler.
      *
      * @param appId                segment routing application ID
      * @param deviceConfiguration  DeviceConfiguration reference