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
{
		/**
		 * the table infomation
		 */
		private TableItemDesign table;
		/**
		 * does the group contains drop cells
		 */
		private boolean[] dropCellsInGroup;
		/**
		 * total row count in the table
		 */
		private int rowCount;