public static void toUpperCase(List<String> l) {
    ListIterator<String> iterator = l.listIterator();
    while (iterator.hasNext()) {
      iterator.set(iterator.next().toUpperCase());
    }
  }
Make list of string lowercase
@param l list of strings, which need to be in lowercase
ambari-server/src/main/java/org/apache/ambari/server/utils/CustomStringUtils.java