Contain tables and autofields

How do I set the autofield for the attached table, please?

->contain(['Orders.OrdersItems' => function(\Cake\ORM\Query $query) {
    return $query->enableAutoFields(true);
}])

But the orders_items field does not contain any items.

'order' => object(App\Model\Entity\Order) id:74 {
   'orders_items' => [ ]
}

Can it be applied to the contained table?