public function setConfig(ConfigInterface $config)
    {
        // get keys & flip
        $configKeys = array_flip($config->keys());
        // put default config
        foreach ($this->defaultConfiguration as $key => $value) {
            if (!isset($configKeys[$key])) {
                $config->set($key, $value);
            }
        }

        $this->config = $config;
    }