itemsRole property
The role attribute each menu item should apply.
The role attribute is used for a11y purposes and should be the same for
each menu item in a group. For selectable menu items the possible roles
are menuitemcheckbox or menuitemradio.
https://www.w3.org/TR/wai-aria-1.1/#menuitemradio
https://www.w3.org/TR/wai-aria-1.1/#menuitemcheckbox
Implementation
@override
final String itemsRole;