|Description||Allows to define the number of items in the cart.
This field becomes mandatory for the shopping cart to be taken into account.
When it is populated, the Shopping cart tab becomes available in the transaction details in the Merchant Back Office.
However, if the other fields that start with vads_product_ are not populated, the tab will not include any information. For this reason, when populating the vads_nb_products field, it is mandatory to populate the other fields that start with vads_product_.