if (isLoginRequired()) {
            return redirectToLogin();
        }

        final Map<String, Object> doc =
                searchHelper.getDocumentByDocId(form.docId, queryFieldConfig.getResponseFields(), getUserBean()).orElse(null);
        final String url = DocumentUtil.getValue(doc, fessConfig.getIndexFieldThumbnail(), String.class);

        SUGGEST;
    }

    /**
     * Returns the response fields.
     *
     * @return The response fields.
     */
    public String[] getResponseFields() {
        return ComponentUtil.getQueryFieldConfig().getResponseFields();
    }