private function filterMethod(?string $method): string
    {
        if ($method === null) {
            return self::METHOD_GET;
        }

        if (! \preg_match("/^[!#$%&'*+.^_`|~0-9a-z-]+$/i", $method)) {
            throw new InvalidArgumentException(\sprintf(
                'Unsupported HTTP method [%s].',
                $method
            ));
        }

        return $method;
    }
private function filterMethod(?string $method): string
    {
        if ($method === null) {
            return self::METHOD_GET;
        }

        if (! \preg_match("/^[!#$%&'*+.^_`|~0-9a-z-]+$/i", $method)) {
            throw new InvalidArgumentException(\sprintf(
                'Unsupported HTTP method [%s].',
                $method
            ));
        }

        return $method;
    }
private function filterMethod ( ? string $ method ) : string { if ( $ method === null ) { return self :: METHOD_GET ; } if ( ! \ preg_match ( "/^[!#$%&'*+.^_`|~0-9a-z-]+$/i" , $ method ) ) { throw new InvalidArgumentException ( \ sprintf ( 'Unsupported HTTP method [%s].' , $ method ) ) ; } return $ method ; }
Validate the HTTP method.

@param null|string $method

@throws \Viserio\Component\Contract\Http\Exception\InvalidArgumentException on invalid HTTP method

@return string
Validate the HTTP method .