Webhook API integration with the Content type application/json(resolved)

Hello, I am working as developer and I have tried to create Webhook API integration via Swagger Studio which uses Content type application/json(resolved) and tried to test it by using the service webhook.cool.

It looks like the functionality does not work for the Content type application/json(resolved), but it works fine for the for the Content type application/json(unresolved). Could you please inform me if this functionality is supported when webhook integration is chosen with the Content type application/json(resolved) or there is an issue with the integration?

Thanks.