code: public List<DynamoDBMapper.FailedBatch> batchSave(Iterable<T> objectsToSave) {
          return mapper.batchWrite(objectsToSave, (Iterable<T>)Collections.<T>emptyList());
      }
docs: Saves the objects given using one or more calls to the batchWriteItem API.
  @param objectsToSave The objects to save.
  @return The list of failed batches.
  @see com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper#batchSave