It's 1.6 indeed, sorry.
In fact in pyamentModule.php there is this :
foreach ($order->product_list as $product) {
$price = Product::getPriceStatic((int)$product['id_product'], false, ($product['id_product_attribute'] ? (int)$product['id_product_attribute'] : null), 6, null, false, true, $product['cart_quantity'], false, (int)$order->id_customer, (int)$order->id_cart, (int)$order->{Configuration::get('PS_TAX_ADDRESS_TYPE')});
etc.
}
How to get each product description on the same way ? Is there any function to retrieve description ?