Bug 202236 When select NULL value for multi-value parameter, cause NPE.
Description: When select NULL value for multi-value parameter, cause NPE. Build number: 2.2.1 Steps to reproduce: 1, New a list parameter, check Allow multi-value, uncheck isRequired 2, Select parameter data type as Date 3, Add some items into list 4, Preview 5, Select Null Value item in list Expected result: Can accept Null value for multi-value parameter Actual result: Cause NPE.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/EngineTask.java
}.visit( (ReportDesignHandle) runnable.getDesignHandle( ) );
	}
	public void close( )
	{
		executionContext.close( );
		EngineLoggerHandler.setLogger( null );
	}
	
	protected IContentEmitter createContentEmitter( ) throws EngineException
	{
		String format = renderOptions.getOutputFormat( );
		if ( format == null )
		{
			format = RenderOption.OUTPUT_FORMAT_HTML;
		}
		ExtensionManager extManager = ExtensionManager.getInstance( );
		boolean supported = false;
		Collection supportedFormats = extManager.getSupportedFormat( );
		Iterator iter = supportedFormats.iterator( );
		while ( iter.hasNext( ) )
		{
			String supportedFormat = (String) iter.next( );
			if ( supportedFormat != null
					&& supportedFormat.equalsIgnoreCase( format ) )
			{
				supported = true;
				break;
			}
		}
		if ( !supported )