code: static String formatCustomID(int hour, int min, int sec, boolean negative) {
          // Create normalized time zone ID - GMT[+|-]hh:mm[:ss]
          StringBuilder zid = new StringBuilder(kCUSTOM_TZ_PREFIX);
          if (hour != 0 || min != 0) {
              if(negative) {
                  zid.append('-');
              } else {
                  zid.append('+');
              }
              // Always use US-ASCII digits
              if (hour < 10) {
                  zid.append('0');
              }
              zid.append(hour);
              zid.append(':');
              if (min < 10) {
                  zid.append('0');
              }
              zid.append(min);
  
              if (sec != 0) {
                  // Optional second field
                  zid.append(':');
                  if (sec < 10) {
                      zid.append('0');
                  }
                  zid.append(sec);
              }
          }
          return zid.toString();
      }
docs: /*
  Returns the normalized custom TimeZone ID