Fix issues found by FindBugs: SIC_INNER_SHOULD_BE_STATIC

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

Change-Id: I9026bed7bb5f3f5cbab08d3277802f25b8d2659e
diff --git a/src/main/java/net/onrc/onos/core/registry/ZookeeperRegistry.java b/src/main/java/net/onrc/onos/core/registry/ZookeeperRegistry.java
index 496ae45..e91ab27 100755
--- a/src/main/java/net/onrc/onos/core/registry/ZookeeperRegistry.java
+++ b/src/main/java/net/onrc/onos/core/registry/ZookeeperRegistry.java
@@ -204,7 +204,7 @@
         }
     }
 
-    protected class ClusterLeaderListener implements LeaderLatchListener {
+    protected static class ClusterLeaderListener implements LeaderLatchListener {
         LeaderLatch latch;
 
         public ClusterLeaderListener(LeaderLatch latch) {