Missing required property on the radio component.

[MrHBS]

Missing required property on the checkbox and radio components. Also the switch component could use aria-required (and aria-readonly/disabled?) I think?

[christophe-g]

While at this, aria-controls would also be very usefull for checkbox.

I can propose a PR if we agree on its scope.

[asyncLiz]

At the moment IDREF aria properties such as aria-controls or aria-labelledby aren't well supported with shadow dom, so I don't think those will be easy features.

Adding required to checkbox and radio groups along with validity seem like a reasonable feature.

[asyncLiz]

Checkbox has required now, radio is still missing it