Entering a negative number of days in the Charting plugin causes OutOfMemoryException

 public static void normaliseDateRange(Map dateMap, int days, Class period)
    {
        // find earliest date, then move it forwards until we hit now
        RegularTimePeriod cursor = RegularTimePeriod.createInstance(period, new Date(System.currentTimeMillis() - days * DateUtils.DAY_MILLIS), RegularTimePeriod.DEFAULT_TIME_ZONE);
        RegularTimePeriod now = RegularTimePeriod.createInstance(period, new Date(), RegularTimePeriod.DEFAULT_TIME_ZONE);

        while (!cursor.equals(now))
        {
            if (!dateMap.containsKey(cursor))
                dateMap.put(cursor, new Integer(0));

            cursor = cursor.next();
        }
    }