Replace stage with other

[alamenai]

I had this piece of code :

     `FXMLLoader signUpLoader = new FXMLLoader();
    signUpLoader.setResources(Configuration.getSignUpBundle());
    signUpLoader.setLocation(Indigo.class.getResource("/com/javafx/pattern/mvc/views/fxml/SignUp.fxml"));
    Parent parent = signUpLoader.load();
    //Create undecorator stage (Using Undecorator library https://arnaudnouard.wordpress.com/2014/12/20/undecorator-bis/)
    Undecorator undecorator = new Undecorator(primaryStage, (Region) parent);

`

As far as i know each constructor parameter has a getter and setter ,but it seems they are absents for first parameter "Stage",because I need to replace the old stage like this undecorator.setStage();