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