code: func ConvertedFromDocker(im *schema.ImageManifest) bool {
  	if im == nil { // nil sometimes sneaks in here due to unit tests
  		return false
  	}
  	ann := im.Annotations
  	_, ok := ann.Get("appc.io/docker/repository")
  	return ok
  }
docs: // ConvertedFromDocker determines if an app's image has been converted
  // from docker. This is needed because implicit docker empty volumes have
  // different behavior from AppC