Whether a group's items render under columnOrSubMenuKey: either the group names it as its
column, or the group is the one keyed by it, which is how a submenu addresses its own group.
TabDropdownMenu picks a column's groups with this and getMenuSectionsWithItems decides which
columns have something to show with it, so "this column renders nothing" can never mean two
different things.
Whether a group's items render under
columnOrSubMenuKey: either the group names it as itscolumn, or the group is the one keyed by it, which is how a submenu addresses its own group.TabDropdownMenupicks a column's groups with this andgetMenuSectionsWithItemsdecides which columns have something to show with it, so "this column renders nothing" can never mean two different things.