Bug 121687 Exception throws when export data in table which inside a grid cell.
Description: Exception throws when export data in table which inside a grid cell. Steps to reproduce: 1. insert a grid. 2. insert one table to one grid cell. 3. insert another table to the other grid cell. 4. export data in two tables. Expected result: Data are exported. Actual result: Exception in: ReportEngineService.getMetaData( )
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/DataExtractionTask.java
implements
			IDataExtractionTask
{
	protected ReportDocumentReader reportDocReader;
	protected ComponentID componentId;
	protected InstanceID instanceId;
	protected String[] selectedColumns;
	protected Report report;
	protected List resultMetaList;
	protected HashMap contentMap;
	
	
	public DataExtractionTask( ReportEngine engine, IReportRunnable runnable,
			ReportDocumentReader reader )
	{
		super( engine, runnable );
		
		
		this.reportDocReader = reader;
		executionContext.setReportDocument( reportDocReader );
		executionContext.setFactoryMode( false );
		executionContext.setPresentationMode( true );
		report = new ReportParser( ).parse( ( (ReportRunnable) runnable )
				.getReport( ) );
		
		populateContent( );
		executionContext.setReport( report );
		setParameterValues( reportDocReader.getParameterValues( ) );