Cancels an existing pickup request in the Maven system. This endpoint can be used to automate pickup request cancelations that originate from outside of the Maven system. A canceled pickup request will be assigned a generic completion status of 'Canceled by TMS'.

If a shipment cannot be found with the refNumber specified, or if the shipment has already been assigned a completion status within the Maven system, then this request will fail with a BAD_REQUEST error response.