post https://marketplace.walmartapis.com/v3/fulfillment/inbound-shipments
Once you’ve converted items to WFS, you can start shipping items inbound to Walmart. To do this, submit an inbound shipment request. The Inbound shipment details when you expect to ship the product and the items and quantities that will be shipped.
Each shipment you send to WFS should have a corresponding Inbound shipment. In this case, a shipment would be considered a direct truckload, LTL shipment, or set of items shipped via parcel on a given day.