JavaFx TreeView with CheckBox and ContextMenu

in the tutorial http://ift.tt/10hbEuA it explain how to create a TreeView with ContextMenu or CheckBox.

but is it possible to have both of them?

when I first copy-paste the code, I learned that I can have only one setCellFactory since they overwrite each other.

    // the following two setCellFactory are copied from the tutorial

    // this create TreeCell with ContextMenu
    treeView.setCellFactory(new Callback<TreeView<String>,TreeCell<String>>(){
        @Override
        public TreeCell<String> call(TreeView<String> p) {
            return new TextFieldTreeCellImpl();
            //the class TextFieldTreeCellImp is a TreeCell with ContextMenu
        }
    });

    // this create TreeCell with CheckBox
    tree.setCellFactory(CheckBoxTreeCell.<String>forTreeView());

then i tried substituting TreeCell with CheckBoxTreeCell

    //class TextFieldTreeCellImpl extends TreeCell<String> {
    class TextFieldTreeCellImpl extends CheckBoxTreeCell<String> {
    ...
    //TreeItem newTag = new TreeItem<String>("New tag");
    CheckBoxTreeItem newTag = new CheckBoxTreeItem<String>("New tag");

but the checkbox didn't appear. it's still a normal treeview.