protected function validateRequestTarget($requestTarget) : void
	{
		if (! \is_string($requestTarget))
		{
			throw new \InvalidArgumentException('HTTP request-target must be a string');
		}
		else if (! \preg_match('/^[\x21-\x7E\x80-\xFF]+$/', $requestTarget))
		{
			throw new \InvalidArgumentException(\sprintf('The given request-target "%s" is not valid', $requestTarget));
		}
	}