Missing docs - Creating shopping product ad

[Darshan Dhabale]

I am using the REST interface. I have created a shopping type campaign and adgroup, now when creating an ad of that type I'm not able to find the docs that define the json to pass to the ad property.
Here the docs are missing details, https://developers.google.com/google-ads/api/rest/reference/rest/v17/Ad#ShoppingSmartAdInfo
Please point me in the right direction.
Thank you