code: public static CompletionStage<Stage> setStylesheet(final Stage stage, final FxmlStylesheet stylesheet) {
          return setStylesheet(stage, stylesheet.getExternalForm());
      }
docs: See {@link #setStylesheet(Stage, String)}
  
  @param stage      The stage to apply the style to
  @param stylesheet The {@link FxmlStylesheet} pointing to the stylesheet to apply
  
  @return A {@link CompletionStage} to have monitoring over the state of the asynchronous operation