#vulnerable code 
                                public boolean within(Date date, String lower, String upper) throws ParseException {
        Date lowerDate = date(lower);
        Date upperDate = date(upper);
        return date != null && date.getTime() >= lowerDate.getTime() && date.getTime() <= upperDate.getTime();
    } 
                            #location 4 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                public boolean within(Date date, String lower, String upper) throws ParseException {
        LOGGER.debug("within({},{},{})", date, lower, upper);
        Date lowerDate = date(lower);
        Date upperDate = date(upper);
        boolean result = date != null && date.getTime() >= lowerDate.getTime() && date.getTime() <= upperDate.getTime();
        LOGGER.debug("within({},{},{})={}", date, lower, upper, result);
        return result;
    }