gateway
Immutable. The Google Cloud IAM Service Account that Gateways serving this config should use to authenticate to other services. This may either be the Service Account's email ({ACCOUNT_ID}@{PROJECT}.iam.gserviceaccount.com) or its full resource name (projects/{PROJECT}/accounts/{UNIQUE_ID}). This is most often used when the service is a GCP resource such as a Cloud Run Service or an IAP-secured service.