final QueryResponseList queryResponseList = (QueryResponseList) documentItems;
        data.setFacetResponse(queryResponseList.getFacetResponse());

        @SuppressWarnings("unchecked")
        final Set<String> highlightQueries = (Set<String>) params.getAttribute(Constants.HIGHLIGHT_QUERIES);
        if (highlightQueries != null) {
            final StringBuilder buf = new StringBuilder(100);
            highlightQueries.stream().forEach(q -> {

    /** A map of listeners for configuration updates. */
    protected Map<String, Supplier<String>> updateConfigListenerMap = new HashMap<>();

    /** A set of names of threads that are currently waiting. */
    protected Set<String> waitingThreadNames = Collections.synchronizedSet(new HashSet<>());

    /**
     * Initializes the SystemHelper.