*
     * @return array of available RankFusionSearcher instances
     */
    protected RankFusionSearcher[] getAvailableSearchers() {
        if (searchers.isEmpty()) {
            logger.warn("No searchers registered");
            return new RankFusionSearcher[0];
        }
        if (availableSearcherNameSet.isEmpty()) {
            return searchers.toArray(new RankFusionSearcher[0]);
        }