Unable to create notification-configuration from API doc example

So I’m evaluating Terraform Cloud and I’m going through the motions of driving everything via api calls. So far so good with creating workspaces, seeding them with variables and initiating runs. I’ve hit a bump with creating notification configurations via the api. I’m going by this example:

Using the sample curl request shortly after the example generic configuration payload, renders me:

{“errors”:[{“status”:“404”,“title”:“not found”}]}

I’m a little confused with the document since the request body section says data.type must be "notification-configuration" but the example payload has "notification-configurations":

I tried plural and singular to no avail. I wanted to find out if others are experiencing this as well when dealing with the notification-configurations api?