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

Change-Id: I1326759bf83a2e4f943ea52df8ebd7e9356c3a93
diff --git a/core/api/src/main/java/org/onosproject/store/service/Serializer.java b/core/api/src/main/java/org/onosproject/store/service/Serializer.java
index 6245175..cac14cb 100644
--- a/core/api/src/main/java/org/onosproject/store/service/Serializer.java
+++ b/core/api/src/main/java/org/onosproject/store/service/Serializer.java
@@ -53,6 +53,24 @@
         return using(Arrays.asList(kryo));
     }
 
+    /**
+     * Creates a new Serializer instance from a KryoNamespace and some additional classes.
+     *
+     * @param namespace kryo namespace
+     * @param classes variable length array of classes to register
+     * @return Serializer instance
+     */
+    static Serializer using(KryoNamespace namespace, Class<?>... classes) {
+        return using(Arrays.asList(namespace), classes);
+    }
+
+    /**
+     * Creates a new Serializer instance from a list of KryoNamespaces and some additional classes.
+     *
+     * @param namespaces kryo namespaces
+     * @param classes variable length array of classes to register
+     * @return Serializer instance
+     */
     static Serializer using(List<KryoNamespace> namespaces, Class<?>... classes) {
         KryoNamespace.Builder builder = new KryoNamespace.Builder();
         namespaces.forEach(builder::register);
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);