code: func (actor Actor) GrantSpaceDeveloperByUsername(spaceGUID string, username string) (Warnings, error) {
  	if actor.Config.UAAGrantType() == string(uaaconst.GrantTypeClientCredentials) {
  		warnings, err := actor.CloudControllerClient.UpdateSpaceDeveloper(spaceGUID, username)
  
  		return Warnings(warnings), err
  	}
  
  	warnings, err := actor.CloudControllerClient.UpdateSpaceDeveloperByUsername(spaceGUID, username)
  	return Warnings(warnings), err
  }
docs: // GrantSpaceDeveloperByUsername makes the provided user a Space Developer in the
  // space with the provided guid.