docs: public void deleteByQuery(String index, String type) throws IOException {
          logger.debug("deleteByQuery [{}]/[{}]", index, type);
  
          String deleteByQuery = "{\n" +
                  "  \"query\": {\n" +
                  "    \"match_all\": {}\n" +
                  "  }\n" +
                  "}";
  
          HttpEntity entity = EntityBuilder.create().setText(deleteByQuery).setContentType(ContentType.APPLICATION_JSON).build();
          Response restResponse = lowLevelClient.performRequest("POST", "/" + index + "/" + type + "/_delete_by_query", Collections.emptyMap(), entity);
          Map<String, Object> response = asMap(restResponse);
          logger.debug("reindex response: {}", response);
      }