protected function mergeOptions(&$config, $options)
    {
        foreach ($config as $paramName => $paramValue) {
            if (isset($options[$paramName])) {
                if (is_array($paramValue)) {
                    $config[$paramName] =  array_merge($config[$paramName], $options[$paramName]);
                } else {
                    $config[$paramName] = $options[$paramName];
                }
            }
        }

        return $config;
    }