protected function validateMethod($method) : void
	{
		if (! \is_string($method))
		{
			throw new \InvalidArgumentException('HTTP method must be a string');
		}
		else if (! \preg_match(HeaderInterface::RFC7230_TOKEN, $method))
		{
			throw new \InvalidArgumentException(\sprintf('The given method "%s" is not valid', $method));
		}
	}