@Contract(pure = true)
  public static boolean isNumeric(@Nullable CharSequence str) {
    if (isEmpty(str)) {
      return false;
    }

    for (int i = 0; i < str.length(); i++) {
      if (!Character.isDigit(str.charAt(i))) {
        return false;
      }
    }
    return true;
  }
@Contract(pure = true)
  public static boolean isNumeric(@Nullable CharSequence str)