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