I think it would be nice to use the webjar for handsontable.
The version that's in GBNG is 0.26.1 and since then they've had 6 releases. Though just for 12.0 being so close if we do this we might want to leave it at 0.26.1.
I added a local webjar like this to evalsys by adding a local webjars servlet to evalsys. Maybe there's some way to do it for wicket but this would be fine too.