code: private void setRowKey(String key, Map<String, AttributeValue> row) {
  		if (row.containsKey(Config._KEY)) {
  			logger.warn("Attribute name conflict:  "
  				+ "attribute {} will be overwritten! {} is a reserved keyword.", Config._KEY);
  		}
  		row.put(Config._KEY, new AttributeValue(key));
  	}
docs: ///////////////////////////////////////////