Trigger is not accepting "notification_webhook" as action field parameter

Steps to reproduce

1. Create a webhook as listed here: 

https://developer.zendesk.com/api-reference/webhooks/webhooks-api/webhooks/#create-or-clone-webhook 

Setting “subscriptions” property as: 

"subscriptions": [

                "conditional_ticket_events"

],

2.  Send a POST request to:  https://my-subdomain.zendesk.com/api/v2/triggers

Create the body according to:

https://developer.zendesk.com/api-reference/ticketing/business-rules/triggers/#create-trigger

Set the action as suggested here to notify a webhook when trigger is fired:

https://developer.zendesk.com/documentation/ticketing/reference-guides/actions-reference/#additional-actions-for-ticket-triggers-and-automations

The body remains as:

{
  "trigger": {
    "title": "Testing",
    "description": "Test Trigger to Notify Webhook",
    "actions": [
      {
        "field": "notification_webhook",
        "value": [
        "My Webhook ID",
        "{\"ticket-title\": \"{{ticket.title}}\",\"test\": \"Sample\"}"
         ]
      }
    ],
    "conditions": {
      "all": [
        {
          "field": "status",
          "operator": "is",
          "value": "new"
        }
      ],
      "any": []
      }
    }
}

Expected behavior:

Trigger is created succesfully

Current behavior:

I'm getting the following response:

{

    "error": "RecordInvalid",

    "description": "Record validation errors",

    "details": {

        "base": [

            {

                "description": "Invalid rule target: notification_webhook"

            }

        ]

    }

}

Am I doing something wrong?