final FilterChain chain) {
        if (!acceptHttpMethod(request, GET)) {
            return;
        }

        if (!ComponentUtil.getFessConfig().isWebApiPopularWord()) {
            writeJsonResponse(HttpServletResponse.SC_BAD_REQUEST, escapeJsonKeyValue(MESSAGE_FIELD, "Unsupported operation."));
            return;
        }

    }

    default void setWebApiPopularWord(final boolean value) {
        setSystemPropertyAsBoolean(Constants.WEB_API_POPULAR_WORD_PROPERTY, value);
    }

    default boolean isWebApiPopularWord() {
        return getSystemPropertyAsBoolean(Constants.WEB_API_POPULAR_WORD_PROPERTY, true);
    }

    default void setCsvFileEncoding(final String value) {