Added Type and ID to support multi layer topology
Fixed checkstyle errors
removed ID . For now we decided to store it in map
Updated javadoc comments

Change-Id: Ieda7cf4054b2b69ed6d39333e9d5c4a1fa4b7601
diff --git a/src/main/java/net/onrc/onos/core/topology/LinkImpl.java b/src/main/java/net/onrc/onos/core/topology/LinkImpl.java
index 4c7e1c5..d0276d1 100644
--- a/src/main/java/net/onrc/onos/core/topology/LinkImpl.java
+++ b/src/main/java/net/onrc/onos/core/topology/LinkImpl.java
@@ -96,4 +96,15 @@
                 getCapacity(),
                 getDstPort().toString());
     }
+
+
+    /**
+     * Returns the type of topology object.
+     *
+     * @return the type of the topology object
+     */
+    @Override
+    public String getType() {
+        throw new UnsupportedOperationException("Not implemented yet");
+    }
 }