MenuItem.submenu constructor
MenuItem.submenu({
Implementation
MenuItem.submenu({
this.key,
this.label,
this.sublabel,
this.toolTip,
this.icon,
this.disabled = false,
this.submenu,
this.onClick,
this.onHighlight,
this.onLoseHighlight,
}) : id = _generateMenuItemId(),
type = 'submenu';