header = ReaderUtil.readLine(reader);
            if (header == null) {
                throwValidationError(messages -> messages.addErrorsInvalidHeaderForRequestFile(GLOBAL, "no header"),
                        () -> asListHtml(this::saveToken));
                return redirect(getClass()); // no-op
            }
            String line;

     * @param property The property name for the message. (NotNull)
     * @param arg0 The parameter arg0 for message. (NotNull)
     * @return this. (NotNull)
     */
    public FessMessages addErrorsInvalidHeaderForRequestFile(String property, String arg0) {
        assertPropertyNotNull(property);
        add(property, new UserMessage(ERRORS_invalid_header_for_request_file, arg0));
        return this;
    }

    /**