how to make ACTIVE - Interface Component.Focusable

[url=https://vaadin.com/api/com/vaadin/ui/Component.Focusable.html]
https://vaadin.com/api/com/vaadin/ui/Component.Focusable.html

On start run, the focus is set to GRID, but the row is not being selected which would populate the FORM.

Please, how would I (input focus) activate the row?
[/url]