Copied in a second complete org.bp.threeten and made writeExternal public.
Not sure why two African zoneids return different observesDaylightSaving when compared to java.util.TimeZone.observesDaylightSaving() so the ZoneRulesTest.testObservesDaylightTimeAllTimezons() skips them and tests all other available zoneIds.
…one.ZoneReader.writeExternal