code: private boolean validBatchGetRequest(Map<Class<?>, List<KeyPair>> itemsToGet) {
          if (itemsToGet == null || itemsToGet.size() == 0) {
              return false;
          }
  
          for (Class<?> clazz : itemsToGet.keySet()) {
              if (itemsToGet.get(clazz) != null && itemsToGet.get(clazz).size() > 0) {
                  return true;
              }
          }
          return false;
      }
docs: Check whether the batchGetRequest meet all the constraints.
  
  @param itemsToGet