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
List ret = new ArrayList( );
		for ( int j = 0; j < row.getCellCount( ); j++ )
		{
			CellDesign cell = row.getCell( j );
			if ( cell != null )
			{
				for ( int m = 0; m < cell.getContentCount( ); m++ )
				{
					ReportItemDesign item = cell.getContent( m );
					if ( item instanceof DataItemDesign )
					{
						String valueExpr = ( ( DataItemDesign ) item )
								.getValue( );
						ret.add( valueExpr );
					} else if ( item instanceof MultiLineItemDesign )
					{
						String valueExpr = ( ( MultiLineItemDesign ) item )
								.getContent( );
						ret.add( valueExpr );
					}
				}
			}
		}
		return ret;
	}
	/**
	 * the outest group which contains drop cells.
	 */
	int outestDropGroup;
	private class TableLayoutEmitter extends ContentEmitterAdapter