Can't load fxml on Macos

[Davide Perini]

Hi all,
this code works well on both Windows and Linux running Java 15 on JavaFX 15.

FXMLLoader fxmlLoader =new FXMLLoader(GUIManager.class.getResource( fxml + 
Constants.FXML)); return fxmlLoader.load();


It doesn't work on Macos returning a nullpointer exception.

Any idea? Why Macos is always the black sheep?

Thanks
Davide