POST request to the /api/esim/order endpoint.items: An array of eSIM items you want to order. Each item should contain the following details:packageId: The ID of the eSIM package you want to order. This is a required field of type string.quantity: The quantity of the eSIM package you want to order. This is a required field of type number.referenceId: The reference ID for the order. This is an optional field of type string. (Your custom reference ID for the order, if needed.)