Bug 135790 ClassCastException in RowData.
ClassCastException is thrown in RowData line 81(IBaseExpression expr = ( IBaseExpression ) valueExpressions.get( index - 1 );).
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/executor/TableItemExecutor.java
CellDesign cellDesign = ( CellDesign ) cell.getGenerateBy( );
			String dropType = cellDesign.getDrop( );
			if ( dropType != null && !"none".equals( dropType ) )
			{
				rowSpan = createDropID( groupIndex, dropType );
			}
			layout.createCell( colId, rowSpan, colSpan, new CellContent( cell,
					cellEmitter ) );
		}
		private int createDropID( int groupIndex, String dropType )
		{
			int dropId = -10 * ( groupIndex + 1 );
			if ( "all".equals( dropType ) )
			{
				dropId--;
			}
			return dropId;
		}
		public void endCell( ICellContent cell )
		{
		}
		public void resolveCellsOfDropDetail( int groupIndex )
		{
			layout.resolveDropCells( createDropID( groupIndex, "detail" ) );
		}
		public void resolveCellsOfDropAll( int groupIndex )
		{
			layout.resolveDropCells( createDropID( groupIndex, "all" ) );
		}
		public IContentEmitter getCellEmitter( )