public static Optional<String> getInstanceId(List<SubjectAlternativeName> sans) {
        // Prefer instance id from SAN URI over the legacy DNS entry
        return getLastSegmentFromSanUri(sans, "athenz://instanceid/")
                .or(() -> getAthenzUniqueInstanceIdFromSanDns(sans));
    }
@return Athenz unique instance id from the Subject Alternative Name extension
vespa-athenz/src/main/java/com/yahoo/vespa/athenz/tls/AthenzX509CertificateUtils.java