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/SinglePacketOutNotification.java b/src/main/java/net/onrc/onos/ofcontroller/proxyarp/SinglePacketOutNotification.java
index d654f67..ab9a9b5 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/proxyarp/SinglePacketOutNotification.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/proxyarp/SinglePacketOutNotification.java
@@ -5,34 +5,53 @@
 // TODO This class is too generic to be handled by ProxyArpService.
 /**
  * Notification to another ONOS instance to send a packet out a single port.
- *
  */
 public class SinglePacketOutNotification extends PacketOutNotification {
 
-	private static final long serialVersionUID = 1L;
-	
-	private final InetAddress address;
-	private final long outSwitch;
-	private final short outPort;
-	
-	public SinglePacketOutNotification(byte[] packet, InetAddress address,
-			long outSwitch, short outPort) {
-		super(packet);
-		
-		this.address = address;
-		this.outSwitch = outSwitch;
-		this.outPort = outPort;
-	}
+    private static final long serialVersionUID = 1L;
 
-	public long getOutSwitch() {
-		return outSwitch;
-	}
+    private final InetAddress address;
+    private final long outSwitch;
+    private final short outPort;
 
-	public short getOutPort() {
-		return outPort;
-	}
+    /**
+     * Class constructor.
+     * @param packet the packet data to send in the packet-out
+     * @param address target IP address if the packet is an ARP packet
+     * @param outSwitch the dpid of the switch to send the packet on
+     * @param outPort the port number of the port to send the packet out
+     */
+    public SinglePacketOutNotification(byte[] packet, InetAddress address,
+            long outSwitch, short outPort) {
+        super(packet);
 
-	public InetAddress getTargetAddress() {
-		return address;
-	}
+        this.address = address;
+        this.outSwitch = outSwitch;
+        this.outPort = outPort;
+    }
+
+    /**
+     * Get the dpid of the switch the packet will be sent out.
+     * @return the switch's dpid
+     */
+    public long getOutSwitch() {
+        return outSwitch;
+    }
+
+    /**
+     * Get the port number of the port the packet will be sent out.
+     * @return the port number
+     */
+    public short getOutPort() {
+        return outPort;
+    }
+
+    /**
+     * Get the target IP address if the packet is an ARP packet.
+     * @return the target IP address for ARP packets, or null if the packet is
+     *         not an ARP packet
+     */
+    public InetAddress getTargetAddress() {
+        return address;
+    }
 }