vaadin-contextmenu getSelectedObj from Vaadin 7 Tabel


after switching from Vaadin 7 to Vaadin 8 I cannot use the old contextmenu add-on, so I tryed the vaadin-contextmenu.
I have started with the demo, this is my source

    com.vaadin.v7.contextmenu.TableContextMenu tableConMen = new com.vaadin.v7.contextmenu.TableContextMenu(table);
    MenuItem I1 = tableConMen.addItem("Add User", ToolsetIcons.ADD, e -> {"Action!"+ e.getCommand().getClass());});

this works, but in the past it was possible to register a listern at the menuItem and I can ask the ContextMenu to get the selected Object (row)
How can I do this right now?? I get the notification that the Item was clicked, but how can I get the selected Object??

Thanks in advance