code: private void tryRegisterThreeTenOld() {
          try {
              tryRegister("javax.time.Instant", "parse");
              tryRegister("javax.time.Duration", "parse");
              tryRegister("javax.time.calendar.LocalDate", "parse");
              tryRegister("javax.time.calendar.LocalTime", "parse");
              tryRegister("javax.time.calendar.LocalDateTime", "parse");
              tryRegister("javax.time.calendar.OffsetDate", "parse");
              tryRegister("javax.time.calendar.OffsetTime", "parse");
              tryRegister("javax.time.calendar.OffsetDateTime", "parse");
              tryRegister("javax.time.calendar.ZonedDateTime", "parse");
              tryRegister("javax.time.calendar.Year", "parse");
              tryRegister("javax.time.calendar.YearMonth", "parse");
              tryRegister("javax.time.calendar.MonthDay", "parse");
              tryRegister("javax.time.calendar.Period", "parse");
              tryRegister("javax.time.calendar.ZoneOffset", "of");
              tryRegister("javax.time.calendar.ZoneId", "of");
              tryRegister("javax.time.calendar.TimeZone", "of");
  
          } catch (Throwable ex) {
              if (LOG) {
                  System.err.println("tryRegisterThreeTenOld: " + ex);
              }
          }
      }
docs: Tries to register ThreeTen ThreeTen/JSR-310 classes v0.6.3 and beyond.