Create a group of line items. Up to 100 line items can be created in a single request. This would allow you to create all of the line items for an entire order (or multiple orders) in a single request.
The request body will be an array, with each entry being a list of properties you want to set for each new line item. Please see the example for more details.
You must set the hs_product_id property when creating a line item. This property needs to be the objectId of a product object, and represents the product being sold.