code: public List<String> readBulk(final List<String> keys) throws Exception {
          List<String> responses = new ArrayList<>(keys.size());
          JanusGraphTransaction transaction = useJanusgraphTransaction ? graph.newTransaction() : null;
  
          try {
              for (String key : keys) {
                  String response = readSingleInternal(key, transaction);
                  responses.add(response);
              }
          } finally {
              if (transaction != null)
                  transaction.close();
          }
          return responses;
      }
docs: Perform a bulk read operation
  @return a list of response codes
  @throws Exception