setAttributeValue(result, fessConfig.getLdapAttrPreferredLanguage(), o -> user.setPreferredLanguage(o.toString()));
                setAttributeValue(result, fessConfig.getLdapAttrDepartmentNumber(), o -> user.setDepartmentNumber(o.toString()));
                setAttributeValue(result, fessConfig.getLdapAttrUidNumber(), o -> user.setUidNumber(DfTypeUtil.toLong(o)));

     * The value is, e.g. departmentNumber <br>
     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     */
    String getLdapAttrDepartmentNumber();

    /**
     * Get the value for the key 'ldap.attr.uidNumber'. <br>
     * The value is, e.g. uidNumber <br>