code: public static SimpleTimeZone getCustomTimeZone(int offset) {
          boolean negative = false;
          int tmp = offset;
          if (offset < 0) {
              negative = true;
              tmp = -offset;
          }
  
          int hour, min, sec;
  
          if (ASSERT) {
              Assert.assrt("millis!=0", tmp % 1000 != 0);
          }
          tmp /= 1000;
          sec = tmp % 60;
          tmp /= 60;
          min = tmp % 60;
          hour = tmp / 60;
  
          // Note: No millisecond part included in TZID for now
          String zid = formatCustomID(hour, min, sec, negative);
  
          return new SimpleTimeZone(offset, zid);
      }
docs: Creates a custom zone for the offset
  @param offset GMT offset in milliseconds
  @return A custom TimeZone for the offset with normalized time zone id