protected static function validateSyntax($json, $file = null)
    {
        $parser = new JsonParser();
        $result = $parser->lint($json);
        if (null === $result) {
            if (defined('JSON_ERROR_UTF8') && JSON_ERROR_UTF8 === json_last_error()) {
                throw new \UnexpectedValueException('"'.$file.'" is not UTF-8, could not parse as JSON');
            }

            return true;
        }

        throw new ParsingException('"'.$file.'" does not contain valid JSON'."\n".$result->getMessage(), $result->getDetails());
    }