WIP: Add Design memo to each Objects

Change-Id: Ic8dd106508b6c3e1f09e82c11d20dd089d37da99
diff --git a/src/main/java/net/onrc/onos/ofcontroller/networkgraph/Device.java b/src/main/java/net/onrc/onos/ofcontroller/networkgraph/Device.java
index 5124f82..e25e812 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/networkgraph/Device.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/networkgraph/Device.java
@@ -5,12 +5,19 @@
 
 import net.floodlightcontroller.util.MACAddress;
 
+/**
+ * Interface of Device Object exposed to the "NB" read-only Topology.
+ *
+ * Everything returned by these interfaces must be either Unmodifiable view,
+ * immutable object, or a copy of the original "SB" In-memory Topology.
+ *
+ */
 public interface Device {
 	public MACAddress getMacAddress();
-	
+
 	public Collection<InetAddress> getIpAddress();
-	
+
 	public Iterable<Port> getAttachmentPoints();
-	
+
 	public long getLastSeenTime();
 }