Datetime values should be handled using `d.Set("attribute_name", aws.TimeValue(output.Thing.AttributeName).Format(time.RFC3339))` (https://github.com/hashicorp/terraform-provider-aws/blob/main/docs/contributing/data-handling-and-conversion.md#root-typestring-and-aws-timestamp)    ```suggestion  \td.Set("created_at", aws.TimeValue(resp.CreatedAt).Format(time.RFC3339))  ```