PortNumber fixes

- hide new PortNumber(short) and use PortNumber.uint16 instead
- added utility to get PortNumber

Change-Id: Ia39fbe6e7126a3d9465d3035a06850c1d54a7f25
diff --git a/src/test/java/net/onrc/onos/core/util/serializers/KryoFactoryTest.java b/src/test/java/net/onrc/onos/core/util/serializers/KryoFactoryTest.java
index 38a37a0..01b27ea 100644
--- a/src/test/java/net/onrc/onos/core/util/serializers/KryoFactoryTest.java
+++ b/src/test/java/net/onrc/onos/core/util/serializers/KryoFactoryTest.java
@@ -48,8 +48,8 @@
 
     private static final Dpid DPID_A = new Dpid(0x1234L);
     private static final Dpid DPID_B = new Dpid(Long.MAX_VALUE);
-    private static final PortNumber PORT_NO_A = new PortNumber((short) 42);
-    private static final PortNumber PORT_NO_B = new PortNumber((short) 65534);
+    private static final PortNumber PORT_NO_A = PortNumber.uint16((short) 42);
+    private static final PortNumber PORT_NO_B = PortNumber.uint16((short) 65534);
     private static final String ONOS_INSTANCE_NAME = "ONOS-Instance-Test";
 
     private static final double SEC_IN_NANO = 1000 * 1000 * 1000.0;