code: func EnableCrossGroupEncoding(e runtime.Encoder, sourceGroup, destGroup string) error {
  	internal, ok := e.(*codec)
  	if !ok {
  		return fmt.Errorf("unsupported encoder type")
  	}
  
  	dest, ok := internal.encodeVersion[destGroup]
  	if !ok {
  		return fmt.Errorf("group %q is not a possible destination group in the given codec", destGroup)
  	}
  	internal.encodeVersion[sourceGroup] = dest
  
  	return nil
  }
docs: // EnableCrossGroupEncoding modifies the given encoder in place, if it is a codec
  // from this package. It allows objects from one group to be auto-decoded into
  // another group. 'destGroup' must already exist in the codec.