JavaFX8 TreeTableView multiple root items

Question

TreeItem<FileModel> root = new TreeItem<FileModel>(playlist);
treeTblViewFiles.setRoot(root);
treeTblViewFiles.setShowRoot(true);

The code above sets one root item, but I need to have several so called root items with expandable list of child items. How do I do that?
Thanks in advance.

Answer 1

You make a parent root, which you don't show.

That parent's children may also be roots, which you show.