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/ArpCacheResource.java b/src/main/java/net/onrc/onos/ofcontroller/proxyarp/ArpCacheResource.java
index 252e66e..242543c 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/proxyarp/ArpCacheResource.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/proxyarp/ArpCacheResource.java
@@ -5,14 +5,22 @@
 import org.restlet.resource.Get;
 import org.restlet.resource.ServerResource;
 
+/**
+ * REST resource to view the IP to MAC mappings in the ARP cache.
+ *
+ */
 public class ArpCacheResource extends ServerResource {
 
-	@Get("json")
-	public List<String> getArpCache() {
-		IProxyArpService arp = (IProxyArpService) getContext().getAttributes().
-				get(IProxyArpService.class.getCanonicalName());
-		
-		return arp.getMappings();
-	}
+    /**
+     * Handler for a REST call to retrieve the ARP cache.
+     * @return list of mappings formatted as a human-readable string.
+     */
+    @Get("json")
+    public List<String> getArpCache() {
+        IProxyArpService arp = (IProxyArpService) getContext().getAttributes()
+                .get(IProxyArpService.class.getCanonicalName());
+
+        return arp.getMappings();
+    }
 
 }