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/parser/EngineIRVisitor.java
Iterator iter = handle.mapRulesIterator( );
		if ( iter == null )
		{
			return;
		}
		MapDesign map = new MapDesign( );
		while ( iter.hasNext( ) )
		{
			MapRuleHandle ruleHandle = (MapRuleHandle) iter.next( );
			MapRuleDesign rule = createMapRule( ruleHandle, defaultStr );
			if ( rule != null )
			{
				map.addRule( rule );
			}
		}
		if ( map.getRuleCount( ) > 0 )
		{
			item.setMap( map );
		}
	}
	/**
	 * create a map rule.
	 * 
	 * @param obj
	 *            map rule in DE.
	 * @return map rule in ENGINE.
	 */
	protected MapRuleDesign createMapRule( MapRuleHandle handle,
			String defaultStr )
	{