Unified API ProductVariant requires a non-existing ID parameter

[Kyngo]

Sylius version affected: As of 1.8 and above

Description

ProductVariant object requires an ID when making a POST /api/v2/admin/product-variants

Steps to reproduce

It can be reproduced in https://master.demo.sylius.com/api/v2/docs if you go to the POST ProductVariant. When trying to make such query in a local environment I get the following error whatever I put in the request body (even if it's empty):

{"code":404,"message":"Invalid identifier value or configuration."}

Possible Solution

Remove the need for this parameter on API Platform