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/executor/transform/group/GroupCalculationUtil.java
* 
	 * groups: (parent, child) LEVEL 0 LEVEL 1 LEVEL 2
	 * ============================================ 0: -,0 0,0 0,0 1: -,2 0,2
	 * 0,2 2: 1,4 1,3 3: 1,5 1,5 4: 2,6 5: 3,7
	 */
	private ResultSetPopulator resultPopoulator;
	
	/**
	 * 
	 * @param query
	 * @param rsMeta
	 */
	GroupCalculationUtil(BaseQuery query, IResultClass rsMeta,
			ResultSetPopulator resultPopoulator)
	{
		this.query = query;
		this.rsMeta = rsMeta;
		groupInformationUtil = new GroupInformationUtil( this );
		this.resultPopoulator = resultPopoulator;
	}
	/**
	 * @param inputStream
	 * @param rsMeta
	 * @param rsCache
	 * @throws DataException
	 */
	GroupCalculationUtil( InputStream inputStream, IResultClass rsMeta,
			ResultSetCache rsCache ) throws DataException
	{
		try