Use this call to update products in a fulfillment. You can optionally push this change to the order level by adding "force_products_update" : true.

Important notes:

• When the product id is not included, all required product fields (name, price, length, etc.) must be included.
• When "force_products_update" : true is not included in the Update Fulfillment call, Delivery Hub only allows the addition of products on the fulfillment level if they are already included on the order level.
• To update a product, send the Update Fulfillment call with the new data in place of the old.
  For example, if a fulfillment includes a pair of jeans in size L and the customer requests size M instead, you can send the Update Fulfillment call with size M listed instead of L, and the product will be updated in Delivery Hub.
• To delete a product on the fulfillment level, send the Update Fulfillment call without the item to delete. An item cannot be deleted if it is already included in a shipment.
  To add a product, add it to the product array.
• To remove an item from one fulfillment and move it to another fulfillment in the same order:
  1. Send the Update Fulfillment call with the item removed from the Products list.
     Do not include "force_products_update" : true (or mark this parameter as false) so the item isn’t removed from the order level.
  2. Send another Update Fulfillment call for the fulfillment you want to move the item to, adding the item to the second fulfillment’s product list.