code: func (user *User) UnmarshalJSON(data []byte) error {
  	var ccUser struct {
  		Metadata internal.Metadata `json:"metadata"`
  	}
  	err := cloudcontroller.DecodeJSON(data, &ccUser)
  	if err != nil {
  		return err
  	}
  
  	user.GUID = ccUser.Metadata.GUID
  	return nil
  }
docs: // UnmarshalJSON helps unmarshal a Cloud Controller User response.