Fix issues found by FindBugs: URF_UNREAD_PUBLIC_OR_PROTECTED_FIELD

http://findbugs.sourceforge.net/bugDescriptions.html#URF_UNREAD_PUBLIC_OR_PROTECTED_FIELD

Note: the fix for IntentMap.changedEvent is actually a workaround - adding
toString() method that refers to the "unread public or protected fields").
The "eventType" and "intent" fields might be used in the future.

Change-Id: I165183fcbefd3db0d01a728f14cbd6b7681a2f3a
diff --git a/src/main/java/net/onrc/onos/apps/bgproute/PtreeNode.java b/src/main/java/net/onrc/onos/apps/bgproute/PtreeNode.java
index b5e4716..9189e3b 100644
--- a/src/main/java/net/onrc/onos/apps/bgproute/PtreeNode.java
+++ b/src/main/java/net/onrc/onos/apps/bgproute/PtreeNode.java
@@ -13,7 +13,7 @@
 
     public int refCount;
 
-    public RibEntry rib;
+    // public RibEntry rib;
     private static final Logger log = LoggerFactory.getLogger(BgpRoute.class);
 
     PtreeNode(byte[] key, int keyBits, int maxKeyOctet) {
@@ -21,7 +21,7 @@
         left = null;
         right = null;
         refCount = 0;
-        rib = null;
+        // rib = null;
         this.key = new byte[maxKeyOctet];
         this.keyBits = keyBits;
         log.debug("inside Ptreenode constructor key {} bits {}", key, keyBits);