A Shipment Item corresponds directly to a Sales Order Item, and represents an item that should be included as part of a shipment to a customer.
id - Integer - The ID of the shipment item
product - Product - The product that the shipment item belongs to
variant - ProductVariant - The product variant that the shipment item belongs to
quantity - Decimal - The amount of this shipment item that should be included as part of a a shipment. Usually, this will be equal to the quantity purchased by the customer.
price - Decimal - The price of the shipment item as recorded by the corresponding sales order item.
total - Decimal - The final amount of money charged to the customer as recorded by the corresponding sales order item.
sales_order_item - SalesOrderItem - The sales order item that the shipment item belongs to.