A single operation (create, update) on a recommendation subscription. `https://developers.google.com/google-ads/api/reference/rpc/v26/RecommendationSubscriptionService/MutateRecommendationSubscription`

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

| Fields ||
|---|---|
| ## `operation` Union field. Required. Create or update operation. `operation` can be only one of the following: ||
| ### `create` | `https://developers.google.com/google-ads/api/reference/rpc/v26/RecommendationSubscription` Create operation: No resource name is expected for the new subscription. |
| ### `update` | `https://developers.google.com/google-ads/api/reference/rpc/v26/RecommendationSubscription` Update operation: The subscription is expected to have a valid resource name. |
| ## `update_mask` | `https://protobuf.dev/reference/protobuf/google.protobuf#field-mask` Optional. FieldMask that determines which resource fields are modified in an update. |