Added a utility method for creating store Serializer from a single KryoNamespace and some additional classes

Change-Id: I1326759bf83a2e4f943ea52df8ebd7e9356c3a93
diff --git a/utils/misc/src/main/java/org/onlab/util/ExtendedSet.java b/utils/misc/src/main/java/org/onlab/util/ExtendedSet.java
index 0ee1278..3dde285 100644
--- a/utils/misc/src/main/java/org/onlab/util/ExtendedSet.java
+++ b/utils/misc/src/main/java/org/onlab/util/ExtendedSet.java
@@ -45,8 +45,8 @@
 
     /**
      * Returns set element that is equal to the specified object.
-     * @param o
-     * @return
+     * @param o object
+     * @return set element that is equal to the input argument or null if no such set element exists
      */
     public E get(Object o) {
         return map.get(o);