ST defect fixes and review comments fixes

Change-Id: Ib8c56a88c19cd9aa23918d0f9e37c89e74cb0d13
diff --git a/src/main/java/org/onosproject/yangutils/utils/io/impl/YangFileScanner.java b/src/main/java/org/onosproject/yangutils/utils/io/impl/YangFileScanner.java
index 98e0444..7af3d77 100644
--- a/src/main/java/org/onosproject/yangutils/utils/io/impl/YangFileScanner.java
+++ b/src/main/java/org/onosproject/yangutils/utils/io/impl/YangFileScanner.java
@@ -38,7 +38,7 @@
      *
      * @param root specified directory
      * @return list of java files
-     * @throws NullPointerException when no files are there
+     * @throws NullPointerException when no files are there.
      * @throws IOException when files get deleted while performing the
      *             operations
      */
@@ -67,9 +67,8 @@
      * @return list of required files
      * @throws IOException when files get deleted while performing the
      *             operations
-     * @throws NullPointerException null pointer access
      */
-    public static List<String> getFiles(String root, String extension) throws NullPointerException, IOException {
+    public static List<String> getFiles(String root, String extension) throws  NullPointerException, IOException {
         List<String> store = new LinkedList<>();
         Stack<String> stack = new Stack<>();
         stack.push(root);