code: public HttpCall<Void> newCall() {
      HttpUrl url =
          pipeline != null
              ? http.baseUrl.newBuilder("_bulk").addQueryParameter("pipeline", pipeline).build()
              : http.baseUrl.resolve("_bulk");
  
      Request request =
          new Request.Builder()
              .url(url)
              .tag(tag)
              .post(RequestBody.create(APPLICATION_JSON, body.readByteString()))
              .build();
  
      return http.newCall(request, maybeFlush);
    }
docs: Creates a bulk request when there is more than one object to store