post https://sandbox.sellingpartnerapi-na.amazon.com/shipping/v2/shipments
Purchases a shipping service and returns purchase related details and documents.
Note: You must complete the purchase within 10 minutes of rate creation by the shipping service provider. If you make the request after the 10 minutes have expired, you will receive an error response with the error code equal to "TOKEN_EXPIRED". If you receive this error response, you must get the rates for the shipment again.