Support Kryo serialization for intent related types

- Implement the protected constructors
- Register the types in KryoFactory

Change-Id: I14214ed1703a8e4b3145625732c74600fc0aba06
diff --git a/src/main/java/net/onrc/onos/api/newintent/MultiPointToSinglePointIntent.java b/src/main/java/net/onrc/onos/api/newintent/MultiPointToSinglePointIntent.java
index 99c1c02..610863a 100644
--- a/src/main/java/net/onrc/onos/api/newintent/MultiPointToSinglePointIntent.java
+++ b/src/main/java/net/onrc/onos/api/newintent/MultiPointToSinglePointIntent.java
@@ -44,6 +44,15 @@
     }
 
     /**
+     * Constructor for serializer.
+     */
+    protected MultiPointToSinglePointIntent() {
+        super();
+        this.ingressPorts = null;
+        this.egressPort = null;
+    }
+
+    /**
      * Returns the set of ports on which ingress traffic should be connected to the egress port.
      *
      * @return set of ingress ports