Fix some checkstyle and PMD errors in the topology module.

Change-Id: Icf037cefdff18256f1234ed2b6eac761d29af7ac
diff --git a/src/main/java/net/onrc/onos/core/topology/HostEvent.java b/src/main/java/net/onrc/onos/core/topology/HostEvent.java
index 8747079..4c8f78d 100644
--- a/src/main/java/net/onrc/onos/core/topology/HostEvent.java
+++ b/src/main/java/net/onrc/onos/core/topology/HostEvent.java
@@ -132,12 +132,13 @@
         if (getClass() != obj.getClass()) {
             return false;
         }
-        HostEvent other = (HostEvent) obj;
 
         if (!super.equals(obj)) {
             return false;
         }
 
+        HostEvent other = (HostEvent) obj;
+
         // XXX lastSeenTime excluded from Equality condition, is it OK?
         return Objects.equals(mac, other.mac) &&
                 Objects.equals(this.attachmentPoints, other.attachmentPoints);