ComputedColumn column = DataBoundColumnUtil.getColumn( columns, expr );
	public ComputedColumnHandle addColumnBinding( ComputedColumn addColumn,			boolean inForce ) throws SemanticException	{		if ( addColumn == null )			return null;		String expr = addColumn.getExpression( );		if ( expr == null )			return null;		List columns = (List) getProperty( BOUND_DATA_COLUMNS_PROP );		if ( columns == null )			return (ComputedColumnHandle) getPropertyHandle(					BOUND_DATA_COLUMNS_PROP ).addItem( addColumn );		ComputedColumn column = DataBoundColumnUtil.getColumn( columns, expr );		if ( column != null && !inForce )		{			return (ComputedColumnHandle) column.handle(					getPropertyHandle( BOUND_DATA_COLUMNS_PROP ), columns							.indexOf( column ) );		}		return (ComputedColumnHandle) getPropertyHandle(				BOUND_DATA_COLUMNS_PROP ).addItem( addColumn );	}