ONOS-509: Match IPV6_SRC, IPV6_DST criteria

* Following classes have been extended to match IPV6_SRC and IPV6_DST criteria:
    - Criteria
    - DefaultTrafficSelector
    - FlowEntryBuilder
    - FlowModBuilder

* Not included in this submission
    - Match of other IPv6-related criteria
    - Set of all IPv6-related criteria (action)

Change-Id: I115829a480356d2037e0fc809595f7a5eec25874
diff --git a/core/api/src/main/java/org/onosproject/net/flow/TrafficSelector.java b/core/api/src/main/java/org/onosproject/net/flow/TrafficSelector.java
index d9b91f6..267fb51 100644
--- a/core/api/src/main/java/org/onosproject/net/flow/TrafficSelector.java
+++ b/core/api/src/main/java/org/onosproject/net/flow/TrafficSelector.java
@@ -115,7 +115,7 @@
         public Builder matchIPProtocol(Byte proto);
 
         /**
-         * Matches a l3 address.
+         * Matches a l3 IPv4 address.
          *
          * @param ip a l3 address
          * @return a selection builder
@@ -123,7 +123,7 @@
         public Builder matchIPSrc(IpPrefix ip);
 
         /**
-         * Matches a l3 address.
+         * Matches a l3 IPv4 address.
          *
          * @param ip a l3 address
          * @return a selection builder
@@ -146,6 +146,21 @@
          */
         public Builder matchTcpDst(Short tcpPort);
 
+        /**
+         * Matches a l3 IPv6 address.
+         *
+         * @param ip a l3 IPv6 address
+         * @return a selection builder
+         */
+        public Builder matchIPv6Src(IpPrefix ip);
+
+        /**
+         * Matches a l3 IPv6 address.
+         *
+         * @param ip a l3 IPv6 address
+         * @return a selection builder
+         */
+        public Builder matchIPv6Dst(IpPrefix ip);
 
         /**
          * Matches on a MPLS label .