code: func (cgi *ConsumergroupInstance) marshalSubscription(topics []string) ([]byte, error) {
  	subscription := make(map[string]int)
  	for _, topic := range topics {
  		subscription[topic] = 1
  	}
  	data, err := json.Marshal(&Registration{
  		Pattern:      RegPatternStatic,
  		Subscription: subscription,
  		Timestamp:    time.Now().Unix(),
  		Version:      RegDefaultVersion,
  	})
  	if err != nil {
  		return nil, err
  	}
  	return data, nil
  }
docs: // Register registers the consumergroup instance in Zookeeper.