code: func (actor Actor) RestartApplication(appGUID string) (Warnings, error) {
  	var allWarnings Warnings
  	_, warnings, err := actor.CloudControllerClient.UpdateApplicationRestart(appGUID)
  	allWarnings = append(allWarnings, warnings...)
  	if err != nil {
  		return allWarnings, err
  	}
  
  	pollingWarnings, err := actor.PollStart(appGUID)
  	allWarnings = append(allWarnings, pollingWarnings...)
  	return allWarnings, err
  }
docs: // RestartApplication restarts an application and waits for it to start.