Java format date as GMT

gistfile1.txt

    private static String convertToGMT(String epoch) {
        Date date = new Date(Long.parseLong(epoch));
        String GMT_FORMAT = "yyyy-MM-dd HH:mm:ss";

        SimpleDateFormat dateFormat = new SimpleDateFormat(GMT_FORMAT);
        dateFormat.setTimeZone(TimeZone.getTimeZone("GMT"));

//        Calendar calendar = Calendar.getInstance();
//        calendar.setTimeInMillis(entityAttribute.toInstant().toEpochMilli());
//        calendar.setTimeZone(TimeZone.getTimeZone(entityAttribute.getZone()));
//        return calendar;


        return dateFormat.format(date);
    }