return stem + ":" + extn;
return stem + ROOT_INT + extn;
  protected static String constructName(String stem, String extn) {    // TODO This should probably end up in a "naming" utility class    // TODO Why don't I do validation here?    if (stem.equals(ROOT_EXT)) {      return extn;    }    return stem + ":" + extn;  } // protected static String constructName(stem, extn)