A Knowledge Graph entity, represented by its machine id.

[Proto definition ![GitHub](https://developers.google.com/site-assets/logo-github.svg)](https://github.com/googleapis/googleapis/blob/master/google/ads/googleads/v26/common/audience_insights_attribute.proto)

| Fields ||
|---|---|
| ## `knowledge_graph_machine_id` | `string` Required. The machine ID (mid) of the Knowledge Graph entity. |