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/impl/QueryExecutor.java
* @return
	 */
	private boolean isGroupFilter( IFilterDefinition filter)
	{
		IBaseExpression expr = filter.getExpression( );
		if ( expr instanceof IConditionalExpression )
		{
			String expr4Exception = ( (ConditionalExpression) expr ).getExpression( )
					.getText( );
			try
			{
				new FilterExpressionParser( null, null ).compileFilterExpression( expr4Exception );
			}
			catch ( DataException e )
			{
				return true;
			}
		}
		return false;
	}
	
	/*
	 * @see org.eclipse.birt.data.engine.impl.IQueryExecutor#getResultMetaData()
	 */
	public IResultMetaData getResultMetaData( ) throws DataException
	{
		assert odiQuery instanceof IPreparedDSQuery
				|| odiQuery instanceof ICandidateQuery
				|| odiQuery instanceof JointDataSetQuery;