{
  ...
  "outputs": {
    "NotificationHubNamespaceConnectionString": {
      "type": "string",
      "value": "[listKeys(resourceId('Microsoft.NotificationHubs/namespaces/notificationHubs/authorizationRules', parameters('notificationHubNamespaceName'), parameters('notificationHubName'), 'DefaultFullSharedAccessSignature'), providers('Microsoft.NotificationHubs', 'namespaces/notificationHubs').apiVersions[0]).primaryConnectionString]"
    }
  }
}