code: func (actor Actor) SetApplicationDropletByApplicationNameAndSpace(appName string, spaceGUID string, dropletGUID string) (Warnings, error) {
  	allWarnings := Warnings{}
  	application, warnings, err := actor.GetApplicationByNameAndSpace(appName, spaceGUID)
  	allWarnings = append(allWarnings, warnings...)
  	if err != nil {
  		return allWarnings, err
  	}
  	_, apiWarnings, err := actor.CloudControllerClient.SetApplicationDroplet(application.GUID, dropletGUID)
  	actorWarnings := Warnings(apiWarnings)
  	allWarnings = append(allWarnings, actorWarnings...)
  
  	if newErr, ok := err.(ccerror.UnprocessableEntityError); ok {
  		return allWarnings, actionerror.AssignDropletError{Message: newErr.Message}
  	}
  
  	return allWarnings, err
  }
docs: // SetApplicationDropletByApplicationNameAndSpace sets the droplet for an application.