findItems = (aItemItems) => {
				aItemItems.forEach((oItem) => {
					if (!oItem.getItemSelectionMode) {
						aItems.push(oItem);
					} else {
						findItems(oItem.getItems());
					}
				});
			}
Returns the list of menu subitems of this item, including items in groups.

@private
@returns {sap.m.MenuItem} List of menu subitems