return new String( namePrefix + "_" + dateTimeString + ".log" );
return new String( directoryName + "ReportEngine_" + dateTimeString + ".log" );
	private static String generateUniqueLogFileName( String namePrefix )	{		SimpleDateFormat df = new SimpleDateFormat("yyyy_MM_dd_HH_mm_ss"); //$NON-NLS-1$		String dateTimeString = df.format( new Date() );				if ( namePrefix == null )			namePrefix = "BIRT_Engine"; //$NON-NLS-1$				return new String( namePrefix + "_" + dateTimeString + ".log" ); //$NON-NLS-1$; $NON-NLS-2$;	}