Refactor: fix the issues reported by static code analyzer

Change-Id: I8421b5d750e14012d30176ddca7a3873539a361b
diff --git a/apps/openstacknode/api/src/main/java/org/onosproject/openstacknode/api/NodeState.java b/apps/openstacknode/api/src/main/java/org/onosproject/openstacknode/api/NodeState.java
index f34bdb7..ed177f1 100644
--- a/apps/openstacknode/api/src/main/java/org/onosproject/openstacknode/api/NodeState.java
+++ b/apps/openstacknode/api/src/main/java/org/onosproject/openstacknode/api/NodeState.java
@@ -78,6 +78,18 @@
         }
     };
 
+    /**
+     * Processes the given node which is under a certain state.
+     *
+     * @param handler openstack node handler
+     * @param osNode openstack node
+     */
     public abstract void process(OpenstackNodeHandler handler, OpenstackNode osNode);
+
+    /**
+     * Transits to the next state.
+     *
+     * @return the next openstack node state
+     */
     public abstract NodeState nextState();
 }