Quay Webhook Templates undocumented, empty fields in body

When creating a webhook type notification, the following text is appended to the text field to assist users:
 

See: https://docs.quay.io/guides/webhook-template.html If specified, a JSON template for formatting the body of the POST

 
 
The link above serves a 404.
 
Additionally, the templating syntax or a guide on how to configure the formatting for the webhook body is un-documented in the Quay docs hosted at access.redhat.com.
 
This access article [1] was offered, but when using the example template from request.json, none of the specified field values are populated in the POST when called.
 
 

$ cat request.json 
{
  "event": "",
  "method": "",
  "config": {
    "url": ""
  },
  "eventConfig": {},
  "title": ""
}

{{}}
{{}}
Raw content from receiving service:

{
  "eventConfig": {},
  "method": "",
  "config": {
    "url": ""
  },
  "event": "",
  "title": ""
}

 
 
1. https://access.redhat.com/articles/4827931