Addressed some checkstyle, PMD and findbugs violations in the ARP module

Change-Id: I194533ba5f96a7631ea662a93cbcbd8a2c84dea9
diff --git a/src/main/java/net/onrc/onos/ofcontroller/proxyarp/ArpReplyNotification.java b/src/main/java/net/onrc/onos/ofcontroller/proxyarp/ArpReplyNotification.java
index a8afc55..48d04e0 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/proxyarp/ArpReplyNotification.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/proxyarp/ArpReplyNotification.java
@@ -5,24 +5,42 @@
 
 import net.floodlightcontroller.util.MACAddress;
 
+/**
+ * Inter-instance notification that an ARP reply has been received. The
+ * notification contains both the IP address and the MAC address.
+ */
 public class ArpReplyNotification implements Serializable {
 
-	private static final long serialVersionUID = 1L;
-	
-	private InetAddress targetAddress;
-	private MACAddress targetMacAddress;
-	
-	public ArpReplyNotification(InetAddress targetAddress, MACAddress targetMacAddress) {
-		this.targetAddress = targetAddress;
-		this.targetMacAddress = targetMacAddress;
-	}
+    private static final long serialVersionUID = 1L;
 
-	public InetAddress getTargetAddress() {
-		return targetAddress;
-	}
+    private InetAddress targetAddress;
+    private MACAddress targetMacAddress;
 
-	public MACAddress getTargetMacAddress() {
-		return targetMacAddress;
-	}
+    /**
+     * Class constructor.
+     * @param targetAddress IP address received from the ARP reply
+     * @param targetMacAddress MAC address received from the ARP reply
+     */
+    public ArpReplyNotification(InetAddress targetAddress,
+            MACAddress targetMacAddress) {
+        this.targetAddress = targetAddress;
+        this.targetMacAddress = targetMacAddress;
+    }
+
+    /**
+     * Returns the IP address of the ARP reply.
+     * @return the IP address
+     */
+    public InetAddress getTargetAddress() {
+        return targetAddress;
+    }
+
+    /**
+     * Returns the MAC address of the ARP reply.
+     * @return the MAC address
+     */
+    public MACAddress getTargetMacAddress() {
+        return targetMacAddress;
+    }
 
 }