public static String getSubjectDnFormat(final SubjectDnPrincipalResolverProperties.SubjectDnFormat format) {
        return switch (format) {
            case RFC1779 -> X500Principal.RFC1779;
            case RFC2253 -> X500Principal.RFC2253;
            case CANONICAL -> X500Principal.CANONICAL;
            case DEFAULT -> null;
        };
    }
Gets subject dn format.

@param format the format
@return the subject dn format
support/cas-server-support-x509-core/src/main/java/org/apereo/cas/adaptors/x509/util/X509AuthenticationUtils.java