private ColumnInfo @Nullable [] getColumnInfos() {
      TableModel model = getModel();
      if (model instanceof SortableColumnModel) {
        return ((SortableColumnModel)model).getColumnInfos();
      }
      else if (getTable() instanceof TreeTable) {
        TreeTableModel treeTableModel = ((TreeTable)getTable()).getTableModel();
        if (treeTableModel instanceof SortableColumnModel) {
          return ((SortableColumnModel)treeTableModel).getColumnInfos();
        }
      }
      return null;
    }
private ColumnInfo @Nullable [] getColumnInfos()