code: func (gv GroupVersion) String() string {
  	// special case the internal apiVersion for the legacy kube types
  	if gv.Empty() {
  		return ""
  	}
  
  	// special case of "v1" for backward compatibility
  	if len(gv.Group) == 0 && gv.Version == "v1" {
  		return gv.Version
  	}
  	if len(gv.Group) > 0 {
  		return gv.Group + "/" + gv.Version
  	}
  	return gv.Version
  }
docs: // String puts "group" and "version" into a single "group/version" string. For the legacy v1
  // it returns "v1".