setAttributeValue(result, fessConfig.getLdapAttrMail(), o -> user.setMail(o.toString()));
                setAttributeValue(result, fessConfig.getLdapAttrEmployeeNumber(), o -> user.setEmployeeNumber(o.toString()));
                setAttributeValue(result, fessConfig.getLdapAttrTelephoneNumber(), o -> user.setTelephoneNumber(o.toString()));

     * comment: LDAP attribute for employee number.
     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     */
    String getLdapAttrEmployeeNumber();

    /**
     * Get the value for the key 'ldap.attr.mail'. <br>
     * The value is, e.g. mail <br>
     * comment: LDAP attribute for mail.