public static List<String> intern(List<String> list) {
    if(list == null) {
      return null;
    }
    List<String> newList = new ArrayList<String>(list.size());
    for(String str : list) {
      newList.add(intern(str));
    }
    return newList;
  }
Return an interned list with identical contents as the given list.
@param list The list whose strings will be interned
@return An identical list with its strings interned.
common/src/java/org/apache/hive/common/util/HiveStringUtils.java