[onos-3494] Implement TCP Flags Criterion to Southbound

Change-Id: I65bdfa7286249dabfc8109faca140a000efd5e48
diff --git a/core/api/src/main/java/org/onosproject/net/flow/criteria/Criteria.java b/core/api/src/main/java/org/onosproject/net/flow/criteria/Criteria.java
index da8e426..84c6c12 100644
--- a/core/api/src/main/java/org/onosproject/net/flow/criteria/Criteria.java
+++ b/core/api/src/main/java/org/onosproject/net/flow/criteria/Criteria.java
@@ -230,6 +230,16 @@
     }
 
     /**
+     * Creates a match on TCP flags using the specified value.
+     *
+     * @param flags TCP flags
+     * @return match criterion
+     */
+    public static Criterion matchTcpFlags(int flags) {
+        return new TcpFlagsCriterion(flags);
+    }
+
+    /**
      * Creates a match on UDP source port field using the specified value.
      *
      * @param udpPort UDP source port