Bug 180118 Enhance to print out source stack trace in preview mode.[0002]
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/utility/BirtUtility.java
{
	/*
	 * none value
	 */
	public final static String NONE = "none"; 
	/**
	 * Add current task in http session
	 * 
	 * @param request
	 * @param task
	 */
	public static void addTask( HttpServletRequest request, IEngineTask task )
	{
		if ( request == null || task == null )
			return;
		try
		{
			
			BaseAttributeBean attrBean = (BaseAttributeBean) request
					.getAttribute( IBirtConstants.ATTRIBUTE_BEAN );
			if ( attrBean == null )
				return;
			String taskid = attrBean.getTaskId( );
			if ( taskid == null )