Update order items quantity

Summary

Allows the partner to update the quantities for order items. The endpoint accepts amendments for multiple items in a single
call. It is recommended that the integrating partner batches all the substitutions for an order in a single call
of this endpoint in order to avoid receiving a rate limit exceeded error.

Usage scenario

Site would like to change quantities of order items and fulfill order partially.
Once quantities are amended order can be accepted.

Business constraints

• Order has to be in the PLACED status.
• An item (identified by id) can be amended only once.
• The final_quantity value has to be less than the original quantity value.
• Unchanged items are not allowed in the request.

Operational constraints

There's a rate limit of 1 request per order per 30 seconds. If you get over the limit, you'll get "Too many requests" error.