Bug 132805 Set descending to outer group will affect inner group.
Description: Set descending to outer group will affect inner group. Steps to reproduce: 1. New a sample datasource and dataset from orders. 2. Drag the dataset to Layout. 3. Add a group on ordernumber, interval 10, descending. 4. Add another group on orderdate, interval day 2, ascending. 5. Preview. Expected result: Data are grouped correctly. Actual result: Inner group didn't work unless you set outer group's sort to asc.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/expression/ColumnReferenceExpression.java
ColumnReferenceExpression( String rowInd, String columnName )
	{
		logger.entering( ColumnReferenceExpression.class.getName( ),
				"ColumnReferenceExpression" ,columnName);
		assert( columnName != null || columnName.length() == 0 );
		m_columnName = columnName;
		m_columnIndex = -1;
		rowIndicator = rowInd; 
		logger.exiting( ColumnReferenceExpression.class.getName( ),
				"ColumnReferenceExpression" );
	}
	
	ColumnReferenceExpression( String rowInd, int columnIndex )
	{
		logger.entering( ColumnReferenceExpression.class.getName( ),
				"ColumnReferenceExpression",
				new Integer( columnIndex ) );
		assert( columnIndex >= 0 );
		m_columnIndex = columnIndex;
		rowIndicator = rowInd;
		logger.exiting( ColumnReferenceExpression.class.getName( ),
				"ColumnReferenceExpression" );
	}
	
	int getType()
	{
		return TYPE_DIRECT_COL_REF;
	}
	
	public String getColumnName( )