code: protected Object getTopRowBean(final List<Integer> row) {
  		// Get root level
  		List<?> lvl = getBeanList();
  		if (lvl == null || lvl.isEmpty()) {
  			return null;
  		}
  
  		// Get root row bean (ie top level)
  		int rowIdx = row.get(0);
  		Object rowData = lvl.get(rowIdx);
  		return rowData;
  	}
docs: Return the top level bean for this row index.
  
  @param row the row index
  @return the root row bean (ie top level) for this index