title: Vaadin 14 grid with checkboxes as rendered components
body: <p>I created a grid that has four columns. The first column shows a name, the other three columns represent different roles. Each of those three columns is filled with check boxes in order to assign a specific role to a specific name.  That's as far as i have come so far.
  In each column and in each row there should only be one selected checkbox allowed. So in total i do have exactly one selection per checkbox column. How do i implement this?</p>