public static Optional<String> getInstanceId(X509Certificate cert) {
        return getInstanceId(X509CertificateUtils.getSubjectAlternativeNames(cert));
    }
@return Athenz unique instance id from an Athenz X.509 certificate (specified in the Subject Alternative Name extension)
vespa-athenz/src/main/java/com/yahoo/vespa/athenz/tls/AthenzX509CertificateUtils.java