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
import org.eclipse.birt.report.model.api.elements.DesignChoiceConstants;
import com.ibm.icu.util.ULocale;
/**
 * Defines an engine task that could be executed, debugged (runs step by step),
 * inform caller for progress, etc.
 */
public abstract class EngineTask implements IEngineTask
{
	public final static String TASK_TYPE = "task_type";
	protected static int id = 0;
	protected String pagination;
	protected final static String FORMAT_HTML = "html";
	/**
	 * is cancel called
	 */
	protected boolean cancelFlag;
	protected int runningStatus;
	/**
	 * a reference to the report engine
	 */
	protected IReportEngine engine;
	/**
	 * logger used to output the message
	 */
	protected Logger log;
	/**
	 * Comment for <code>locale</code>
	 */
	protected Locale locale = Locale.getDefault( );
	/**