CANNOT_CREATE_DEPRECATED_ADS Error while calling Google ads rest API

I am trying to create ads in Google using REST Api. As per the REST API documentation passing the following request body.

{ "operations": [     {         "create": {             "adGroup": "customers/*********/adGroups/*********",             "status": "PAUSED",             "ad": {                 "expandedTextAd": {                     "headlinePart1": "Example heading",                     "headlinePart2": "Exmaple heading 2",                     "description": "Sample description about ad"                 },                 "finalUrls": [                     "https://www.example.com"                 ]             }         }     } ], "partialFailure": false, "validateOnly": true } 

Endpoint: https://googleads.googleapis.com/v11/customers/{customer_id}/adGroupAds:mutate

Anyone can suggest what I am missing?