{
  "type": "impersonated_service_account",
  "service_account_impersonation_url": "https://iamcredentials.googleapis.com/v1/projects/-/serviceAccounts/service_account_name@namespace.iam.gserviceaccount.com:generateAccessToken",
  "source_credentials": {
    "client_id": "client123",
    "client_secret": "clientSecret123",
    "refresh_token": "refreshToken123",
    "type": "authorized_user"
  }
}