protected function normalizeConfig(array $config)
    {
        foreach ($this->configModel as $elmt => $settings) {
            if (!isset($config[$elmt])) {
                $config[$elmt] = $settings['default'];
            }
        }

        foreach ($config as $elmtName => $value) {
            if (!isset($this->configModel[$elmtName])) {
                unset($config[$elmtName]);
            }
        }

        return $config;
    }