Bug 202038 errors occurred when preview the attached design file.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/executor/transform/pass/ResultSetProcessUtil.java
if ( this.populator.getGroupProcessorManager( )
				.getGroupCalculationUtil( )
				.getSortSpec( ) != null
				&& this.populator.getGroupProcessorManager( )
						.getGroupCalculationUtil( )
						.getSortSpec( )
						.length( ) > 0 )
		{
			PassUtil.pass( this.populator,
					new OdiResultSetWrapper( populator.getResultIterator( ) ),
					true,
					session );
			this.groupingDone = true;
		}
	}
	/**
	 * 
	 * @throws DataException
	 */
	private void doGroupFiltering( ) throws DataException
	{
		if ( ! groupingDone )
		{
			PassUtil.pass( this.populator,
					new OdiResultSetWrapper( populator.getResultIterator( ) ),
					true, session );
			groupingDone = true;
		}
		if ( this.populator.getQuery( ).getGrouping( ) != null