code: public <T> ESDatas<T> searchScroll(String scroll,String scrollId ,Class<T> type) throws ElasticSearchException{
  
  		if(!this.client.isV1()) {
  			StringBuilder entity = new StringBuilder();
  			entity.append("{\"scroll\" : \"").append(scroll).append("\",\"scroll_id\" : \"").append(scrollId).append("\"}");
  			RestResponse result = this.client.executeRequest("_search/scroll", entity.toString(), new ElasticSearchResponseHandler(type));
  			return ResultUtil.buildESDatas(result,type);
  		}
  		else {
  			StringBuilder path = new StringBuilder();
  			path.append("_search/scroll?scroll=").append( scroll ).append( "&scroll_id=" ).append( scrollId);
  			RestResponse result = this.client.executeHttp(path.toString(), ClientUtil.HTTP_GET, new ElasticSearchResponseHandler(type));
  			return ResultUtil.buildESDatas(result, type);
  		}
  	}
docs: scroll search
  https://www.elastic.co/guide/en/elasticsearch/reference/6.2/search-request-scroll.html
  @param scroll
  @param scrollId
  @param type
  @param <T>
  @return
  @throws ElasticSearchException