private function validateTypeAndService(array $config, $path)
    {
        if (!isset($config['type']) && !isset($config['service'])) {
            throw new InvalidConfigurationException(sprintf('You must set one of "type" or "service" for "%s"', $path));
        }
        if (isset($config['type']) && isset($config['service'])) {
            throw new InvalidConfigurationException(sprintf('You cannot set both "type" and "service" for "%s" - please choose one.', $path));
        }
    }