Adobe Sign Webhook creation error

I am creating a webhook but I get the error:

{"code":"INVALID_WEBHOOK_URL","message":"Validation for webhook url failed. Please make sure that the webhook url responds with a valid HTTP response code and a valid client id. Request id: c9189855-0749-4fa4-8f09-0edd1cfc7d4d."}

This is the code of the webhook endpoint, it does the validation as shown in the reference, can it be that the endpoint cannot be from Google App Scripts?

function doGet(e) {
  const adobeClientId = e.headers['x-adobe-sign-clientid'];

  const response = ContentService.createTextOutput("Success")
      .setMimeType(ContentService.MimeType.TEXT).setHeader("x-adobe-sign-clientid", adobeClientId);

  return response;
}