public Optional<Documents> ids(Map<String, List<String>> indexIds) {
        Map<String, List<String>> map = new HashMap<>();
        indexIds.forEach((indexName, ids) -> {
            map.put(indexNameConverter.apply(indexName), ids);
        });
        return es.get().documents().mget(TYPE, map);
    }
Provide to get documents from multi indices by IDs.
@param indexIds key: indexName, value: ids list
@return Documents
@since 9.2.0
oap-server/server-library/library-client/src/main/java/org/apache/skywalking/oap/server/library/client/elasticsearch/ElasticSearchClient.java