code: public Map<String, List<Object>> batchLoad(Map<Class<?>, List<KeyPair>> itemsToGet) {
          return batchLoad(itemsToGet, this.config);
      }
docs: Retrieves the attributes for multiple items from multiple tables using
  their primary keys.
  {@link AmazonDynamoDB#batchGetItem(BatchGetItemRequest)} API.
  
  @see #batchLoad(Map, DynamoDBMapperConfig)