code: public Node getViewWithoutRootContainer() {
  
  		final ObservableList<Node> children = getView().getChildrenUnmodifiable();
  		if (children.isEmpty()) {
  			return null;
  		}
  
  		return children.listIterator().next();
  	}
docs: Scene Builder creates for each FXML document a root container. This
  method omits the root container (e.g. {@link AnchorPane}) and gives you
  the access to its first child.
  
  @return the first child of the {@link AnchorPane} or null if there are no
  children available from this view.