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
layoutEngine.setOption(
						IPDFRenderOption.OUTPUT_DISPLAY_NONE,
						outputDisplayNone );
			}
		}
		layoutEngine.setOption( TASK_TYPE,  new Integer(taskType));
		return layoutEngine;
	}
	protected void loadDesign( )
	{
		if ( runnable != null )
		{
			ReportDesignHandle reportDesign = executionContext.getDesign( );
			
			Iterator iter = reportDesign.includeScriptsIterator( );
			while ( iter.hasNext( ) )
			{
				IncludeScriptHandle includeScript = (IncludeScriptHandle) iter
						.next( );
				String fileName = includeScript.getFileName( );
				executionContext.loadScript( fileName );
			}
			
			ReportScriptExecutor.handleInitialize( reportDesign,
					executionContext );
		}
	}
	protected void prepareDesign( )
	{
		ReportDesignHandle reportDesign = executionContext.getDesign( );