You are building an order-ingestion service that reads messages from a queue and writes each order document to a Cosmos DB for NoSQL container partitioned by /orderId. Because the queue guarantees at-least-once delivery, the same message can be delivered more than once, and the service must never create duplicate documents or throw a 409 Conflict on the second delivery. Each redelivery contains the identical, complete order payload. Which single write operation should the service use for maximum efficiency and correctness?