code: public void index(String indexName, String indexType, String... json) {
          index(
                  Arrays.stream(json)
                          .map(item -> new IndexRequest.IndexRequestBuilder(indexName, indexType, item).build())
                          .collect(toList())
          );
      }
docs: Index documents
  
  @param indexName target index
  @param indexType target index name
  @param json      document represented as JSON