/**
     * Prepares a multi-search request builder.
     *
     * @return the multi-search request builder
     */
    @Override
    public MultiSearchRequestBuilder prepareMultiSearch() {
        return client.prepareMultiSearch();
    }

    /**
     * Prepares an explain request builder for a specific document.
     *
     * @param index the index name
     * @param id    the document ID