code: void formatTimeZone_v(StringBuilder b, ZonedDateTime d, int width) {
      if (width != 1 && width != 4) {
        return;
      }
      
      ZoneId zone = d.getZone();
      Name variants = getTimeZoneName(zone.getId(), d, width == 4);
      String name = variants == null ? null : variants.generic();
  
      if (name != null) {
        b.append(name);
      } else {
        // Falls back to 'O' or 'OOOO'.
        formatTimeZone_O(b, d, width);
      }
    }
docs: Timezone as short / long generic non-location format.