Bug 177504 Engine doesn't provide SubQuery for extended item
Engine doesn't provide SubQuery for extended item, so chart can't use container's binding to execute the query. If possible, engine could provide an option for extended item to choose whether engine could create the query, so extended item won't create SubQuery by itself.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/data/dte/ReportQueryBuilder.java
*/
		public Object visitGridItem( GridItemDesign grid, Object value )
		{
			BaseQueryDefinition query = createQuery( grid, value );
			for ( int i = 0; i < grid.getRowCount( ); i++ )
			{
				build( query, grid.getRow( i ) );
			}
			
			finishVisit( grid, query );			
			if ( query != value )
			{
				return new IBaseQueryDefinition[]{ query };
			}
			return null;
		}
		/*
		 * (non-Javadoc)
		 * 
		 * @see org.eclipse.birt.report.engine.ir.IReportItemVisitor#visitImageItem(org.eclipse.birt.report.engine.ir.ImageItemDesign)
		 */
		public Object visitImageItem( ImageItemDesign image, Object value )
		{
			BaseQueryDefinition query = createQuery( image, value );
			if ( image.getImageSource( ) == ImageItemDesign.IMAGE_EXPRESSION )
			{
				String newImageExpression = transformExpression( image.getImageExpression( ), query, null );
				String newImageFormat = transformExpression( image.getImageFormat( ), query, null );
				image.setImageExpression( newImageExpression, newImageFormat );
			}