code: func NonConvertibleFields(annotations map[string]string) map[string]string {
  	nonConvertibleKeys := map[string]string{}
  	for key, value := range annotations {
  		if strings.HasPrefix(key, core.NonConvertibleAnnotationPrefix) {
  			nonConvertibleKeys[key] = value
  		}
  	}
  	return nonConvertibleKeys
  }
docs: // NonConvertibleFields iterates over the provided map and filters out all but
  // any keys with the "non-convertible.kubernetes.io" prefix.