public function setDefaultStringFormat($format)
    {
        $formats = static::getSupportedStringFormats();

        $format = strtoupper($format);
        if (!in_array($format, $formats)) {
            throw new InvalidArgumentException(sprintf('Given "%s" default string format is not supported. Only "%s" are valid string formats.', $format, implode(', ', $formats)));
        }

        $this->defaultStringFormat = $format;
    }