public static function getDefaultLanguage()
    {
        if (!is_null(self::$defaultLanguage)) {
            return self::$defaultLanguage;
        }

        if (!file_exists(self::$defaultLanguageFile)) {
            throw new \LogicException('Default language file '.self::$defaultLanguageFile.' does not exist');
        }

        self::$defaultLanguage = file_get_contents(self::$defaultLanguageFile);
        return self::$defaultLanguage;
    }