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
return false;
		}
		/**
		 * scan the group header to see if the group has any drop cells.
		 * 
		 * @param group
		 *            group to be scaned.
		 * @return true, the group has drop cells, false, no.
		 */
		private boolean hasDropCellsInGroup( TableGroupDesign group )
		{
			TableBandDesign header = group.getHeader( );
			if ( header != null )
			{
				for ( int i = 0; i < header.getRowCount( ); i++ )
				{
					RowDesign row = header.getRow( i );
					if ( row != null && hasDropCellsInRow( row ) )
					{
						return true;
					}
					return false;
				}
			}
			return false;
		}
	}
	/*
	 * (non-Javadoc)
	 *