Adding device type

Adding device type on port(eg Ethernet Port,TPort,WPort), Link(Ethernet,Optical..) and Switch(Ethernet,Optical)
Updated Serializers.
Fixed javadoc issue for Enums.

ONOS-1428

Change-Id: Id3e3094f1fbf90154fff9a61e3c0ca36be69c281
diff --git a/src/main/java/net/onrc/onos/core/topology/LinkType.java b/src/main/java/net/onrc/onos/core/topology/LinkType.java
new file mode 100644
index 0000000..1c9d9d1
--- /dev/null
+++ b/src/main/java/net/onrc/onos/core/topology/LinkType.java
@@ -0,0 +1,16 @@
+package net.onrc.onos.core.topology;
+
+public enum LinkType {
+    /**
+     * Ethernet link is link between {@link PortType.ETHERNET_PORT}.
+     */
+    ETHERNET_LINK,
+    /**
+     * WDM Link is link between {@link PortType.WDM_PORT}.
+     */
+    WDM_LINK,
+    /**
+     * This link is link between {@link PortType.ETHERNET_PORT} and {@link PortType.TRANSPONDER_PORT}.
+     */
+    PACKET_TPORT_LINK;
+}