Network Graph Refactoring: Northbound API cleanup
 * Renamed/shortened methods:
   Link.getSourcePort() -> getSrcPort()
   Link.getDestinationPort() -> getDstPort()
   Link.getSourceSwitch() -> getSrcSwitch()
   Link.getDestinationSwitch() -> getDstSwitch()

 * Added Javadoc comments

 * Removed deprecated and unused methods:
   Link.getSourceSwitchDpid()
   Link.getSorcePortNumber()
   Link.getDestinationSwitchDpid()
   Link.getDestinationPortNumber()
   NetworkGraph.getOutgoingLinksFromSwitch()
   NetworkGraph.getIncomingLinksFromSwitch()

 * Moved method LinkEvent.getLink(NetworkGraph graph)
   to NetworkGraph.getLink()

Change-Id: Ibedba53fc6cd04d77f508ee67d41b2cfa515d3fc
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 cd5ddf8..c6e1ec2 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/networkgraph/Device.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/networkgraph/Device.java
@@ -15,12 +15,35 @@
  *
  */
 public interface Device {
-	public MACAddress getMacAddress();
+    /**
+     * Get the device MAC address.
+     *
+     * @return the device MAC address.
+     */
+    public MACAddress getMacAddress();
 
-	public Collection<InetAddress> getIpAddress();
+    /**
+     * Get the device IP addresses.
+     *
+     * @return the device IP addresses.
+     */
+    public Collection<InetAddress> getIpAddress();
 
-	// Add requirement for Iteration order? Latest observed port first.
-	public Iterable<Port> getAttachmentPoints();
+    /**
+     * Get the device attachment points.
+     *
+     * Add requirement for Iteration order? Latest observed port first.
+     *
+     * @return the device attachment points.
+     */
+    public Iterable<Port> getAttachmentPoints();
 
-	public long getLastSeenTime();
+    /**
+     * Get the device last seen time.
+     *
+     * TODO: what is the time definition?
+     *
+     * @return the device last seen time.
+     */
+    public long getLastSeenTime();
 }