Bulk Update Deliveries

Apply updates to up to 100 deliveries in a single request. Each item is keyed by exactly one of deliveryId or packageExternalIdentifier (your own id set on the package at creation), plus the same field set as the single-delivery endpoint. The per-item result echoes back the key you sent under deliveryId. Per-item failures come back as a structured error in the response and do not affect the rest of the batch.