woothemes/woocommerce — pull request #5072 by paullryan (2014-03-06 22:16:11+00:00)
Title: Filtering on product_id in Orders REST API

A useful feature for reports is to allow filtering on orders by {{line_items.product_id}}. As items are not pulled until after the initial query this filter is applied as a post filter so limit's may not be respected instead this is intended to give users just the orders for products they want.

This works well for implementations were different products belong to different groups and need to have the api route the only the relevant orders to these groups.