public static boolean exists( List columns, String columnName )
private static boolean exists( List columns, String columnName )
	public static boolean exists( List columns, String columnName )	{		if ( ( columns == null ) || ( columns.size( ) == 0 ) )			return false;		for ( int i = 0; i < columns.size( ); i++ )		{			ComputedColumn column = (ComputedColumn) columns.get( i );			if ( columnName.equals( column.getName( ) ) )				return true;		}		return false;	}