code: func (m DeserializedManifestList) Payload() (string, []byte, error) {
  	var mediaType string
  	if m.MediaType == "" {
  		mediaType = v1.MediaTypeImageIndex
  	} else {
  		mediaType = m.MediaType
  	}
  
  	return mediaType, m.canonical, nil
  }
docs: // Payload returns the raw content of the manifest list. The contents can be
  // used to calculate the content identifier.