Kibana ECK OIDC with DEX

Elastic Orchestration Elastic Cloud on Kubernetes (ECK)
7

The login succeeded but we need to extract the DN from "federated_claim" field "user_id".

{
  "type": "server",
  "timestamp": "2020-07-20T15:35:38,047Z",
  "level": "TRACE",
  "component": "o.e.x.s.a.o.OpenIdConnectAuthenticator",
  "cluster.name": "test",
  "node.name": "test-es-default-0",
  "message": "Successfully retrieved user information: [{\"at_hash\":\"removed\",\"federated_claims\":{\"user_id\":\"cn=achim.admin,ou=People,dc=removed,dc=de\",\"connector_id\":\"dwp_ldap_openldap\"},\"sub\":\"removed\",\"aud\":\"kibana\",\"email_verified\":true,\"iss\":\"https:\\/\\/dex.test.fi-ts.io\\/dex\",\"name\":\"test000\",\"groups\":[\"testsecu\",\"dwpstwpdir\",\"k8s_kaas-admin\",\"test_kaas-all-all-admin\",\"test_prmt-all-all-admin\",\"test_k8s-test-all-clusteradmin\",\"test_k8s-qa$poc-all-clusteradmin\",\"test_k8s-dwp$poc-all-clusteradmin\",\"test_k8s-prod$poc-all-clusteradmin\"],\"exp\":1595302537,\"iat\":1595259337,\"nonce\":\"removed\",\"email\":\"achim.admin@removed\"}]",
}

What would be the correct syntax to read input federated_claims->user_id into claims.dn?

                claims:
                    principal: name
                    groups: groups
                    mail: email
                    dn: federated_claims.user_id # What is the syntax required here?

P.S. The encoded JWT token structure:

# {
#   "iss": "https://dex.test",
#   "sub": "test",
#   "aud": "auth-go-cli",
#   "exp": 1594428593,
#   "iat": 1594385393,
#   "at_hash": "test",
#   "email": "achim.admin@test.de",
#   "email_verified": true,
#   "groups": [
#     "k8s_kaas-admin",
#   ],
#   "name": "test000",
#   "federated_claims": {
#     "connector_id": "test_ldap_openldap",
#     "user_id": "cn=achim.admin,ou=People,dc=test,dc=de"
#   }
# }