docs: public QueryResponse query(QueryRequest request)
              throws BceClientException, BceServiceException {
          checkNotNull(request, "request should not be null.");
          InternalRequest httpRequest = createRequestUnderInstance(HttpMethodName.POST, 
                                                      MolaDbConstants.URI_TABLE,
                                                      request.getTableName(),
                                                      MolaDbConstants.URI_ITEM);
          httpRequest.addParameter(MolaDbConstants.URI_QUERY, null);
          fillInHeadAndBody(request, httpRequest);
          QueryResponse ret = this.invokeHttpClient(httpRequest, QueryResponse.class);
          return ret;
      }