private static BiFunction<Character, Integer, String> setOf(int... numbers) {
    return  (letter, count) -> {
      if (ArrayUtil.indexOf(numbers, count) >= 0) return null;
      final String expected = StringUtil.join(numbers, ", ");
      return InspectionGadgetsBundle.message("inspection.incorrect.date.format.wrong.number.of.letters", letter, expected, count);
    };
  }
private static BiFunction<Character, Integer, String> setOf(int... numbers)