default ColumnGroup getColumnGroup(String type) {
        for (int i = 0; i < ((UIComponent) this).getChildCount(); i++) {
            UIComponent child = ((UIComponent) this).getChildren().get(i);
            if (child instanceof ColumnGroup) {
                ColumnGroup colGroup = (ColumnGroup) child;
                if (Objects.equals(type, colGroup.getType())) {
                    return colGroup;
                }
            }
        }

        return null;
    }
Return each {@link Row} in a Column Group.
@param context  the {@link FacesContext}
@param cg the {@link ColumnGroup} to get
@param skipUnrendered If unrendered components should be skipped
@param callback The callback, which will be invoked for each row. If it returns false, the algorithm will be cancelled
@return false when the algorithm was cancelled
primefaces/src/main/java/org/primefaces/component/api/ColumnAware.java