}
        try {
            final ServletContext servletContext = ComponentUtil.getComponent(ServletContext.class);
            servletContext.setSessionTrackingModes(
                    fessConfig.getSessionTrackingModesAsSet().stream().map(SessionTrackingMode::valueOf).collect(Collectors.toSet()));
        } catch (final Throwable t) {
            logger.warn("Failed to set SessionTrackingMode.", t);
        }

        return split(getIndexerLanguageFields(), ",").get(stream -> stream.map(String::trim).toArray(n -> new String[n]));

    }

    String getSessionTrackingModes();

    default Set<String> getSessionTrackingModesAsSet() {
        return split(getSessionTrackingModes(), ",")
                .get(stream -> stream.map(s -> s.trim().toUpperCase(Locale.ENGLISH)).collect(Collectors.toSet()));
    }