public StreamResponse download(final FileAccessForm form) {
        final File file = getTargetFile(form.fileName).get();
        if (file == null) {
            throwValidationError(messages -> messages.addErrorsTargetFileDoesNotExist(GLOBAL, form.fileName), this::asListHtml);
            return null;
        }
        validate(form, messages -> {}, this::asListHtml);
        verifyTokenKeep(this::asListHtml);

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

    /**