private static AthenzIdentity getIdentityFromSanEmail(String email) {
        int separator = email.indexOf('@');
        if (separator == -1) throw new IllegalArgumentException("Invalid SAN email: " + email);
        return AthenzIdentities.from(email.substring(0, separator));
    }
Utility methods for Athenz issued x509 certificates

@author bjorncs
vespa-athenz/src/main/java/com/yahoo/vespa/athenz/tls/AthenzX509CertificateUtils.java