Webhook creation with header authentication using API

Hello,

I am trying to create a webhook using API as mentioned in https://developer.jamf.com/jamf-pro/reference/createwebhookbyid with <authentication_type>HEADER</authentication_type>

I am unable to find any documentation on how to pass the header information in the API. As per https://learn.jamf.com/en-US/bundle/jamf-pro-documentation-current/page/Webhooks.html

header information needs to be sent as key value pairs but not sure how to pass in the API. 

I get this error,