Fixed some PMD issues in the SDN-IP module

Change-Id: Iaf002e70c1a00f0008edef5e77b91579acf146aa
diff --git a/src/main/java/net/onrc/onos/apps/bgproute/Path.java b/src/main/java/net/onrc/onos/apps/bgproute/Path.java
index 3ecf7c7..f96e0b0 100644
--- a/src/main/java/net/onrc/onos/apps/bgproute/Path.java
+++ b/src/main/java/net/onrc/onos/apps/bgproute/Path.java
@@ -11,12 +11,12 @@
 
 public class Path {
 
-    private Interface dstInterface;
-    private InetAddress dstIpAddress;
-    private int numUsers = 0;
+    private final Interface dstInterface;
+    private final InetAddress dstIpAddress;
+    private int numUsers; // initialized to 0
 
-    private List<PushedFlowMod> flowMods = null;
-    private boolean permanent = false;
+    private List<PushedFlowMod> flowMods; // initialized to null
+    private boolean permanent; // initialized to false
 
     public Path(Interface dstInterface, InetAddress dstIpAddress) {
         this.dstInterface = dstInterface;