code: public static Pane loadFxmlPane(final Class<? extends AbstractFXController> controllerClass) throws CouldNotPerformException {
          return loadFxmlPaneAndControllerPair(loadDefaultFXML(controllerClass), controllerClass, DEFAULT_CONTROLLER_FACTORY).getKey();
      }
docs: Method load the pane of the given fxml file.
  
  @param controllerClass the controller of the fxml pane.
  
  @return the new pane.
  
  @throws CouldNotPerformException is thrown if something went wrong like for example the fxml file does not exist.