Hello Sato-san,
As you know, tz database 2018a flipped Europe/Dublin winter/summer time
rules. There were many messages posted in the tz mailing list, and Paul
Eggert decided to revert the change in tz database 2018c. For future
releases, it looks he want to add a zic build option to swap the rule.
We also discussed what to do in CLDR project. For now, we decided not to
make any changes for Europe/Dublin in CLDR release 33 (GA in March 2018)
at least. We don't have a solid plan for post CLDR 33 releases.
My understanding is that OpenJDK also consumes CLDR zone name data. Is
this true? If so, do you have any input for post CLDR 33 releases?
-Yoshito (Unicode CLDR/ICU project)