Enum describing possible not empty errors.

[Proto definition ![GitHub](https://developers.google.com/site-assets/logo-github.svg)](https://github.com/googleapis/googleapis/blob/master/google/ads/googleads/v25/errors/not_empty_error.proto)

| Enums ||
|---|---|
| ## `EMPTY_LIST` | Empty list. |
| ## `UNKNOWN` | The received error code is not known in this version. |
| ## `UNSPECIFIED` | Enum unspecified. |