protected function mergeGroupConfig(array $groupConfig): array
    {
        $config = $this->config;

        $config['hostname'] = $groupConfig['hostname'] ?? null;
        $config['prefix'] = $groupConfig['prefix'] ?? null;
        $config['namespace'] = $groupConfig['namespace'] ?? null;

        if( array_key_exists('middleware', $groupConfig) ){

            if( array_key_exists('middleware', $config) ){
                $config['middleware'] = array_merge($config['middleware'], $groupConfig['middleware']);
            }

            else {
                $config['middleware'] = $groupConfig['middleware'];
            }
        }

        return $config;
    }