post https://marketplace.walmartapis.com/v3/ca/orders//acknowledgeLines
You can use this API to acknowledge an order line, including all its quantities. Partial acknowledgment is not allowed — all quantities of an order line must be acknowledged.
Walmart requires sellers to acknowledge orders within four hours of receipt, except in extenuating circumstances. The response to a successful call contains the acknowledged order.
In general, only orders that are in a Created state should be acknowledged. As a good practice, acknowledge your orders to avoid underselling.
Orders with line items that are shipped or canceled should not be re-acknowledged.