The JDK 1.1-compatible behavior for the "EST," "MST," and "HST" time zones has been removed. Previously, this behavior could be enabled using the `sun.timezone.ids.oldmapping` system property, but this property is no longer operational in this release. In general, the use of all legacy [Three-letter time zone IDs](https://docs.oracle.com/en/java/javase/24/docs/api/java.base/java/util/TimeZone.html#three-letter-time-zone-ids-heading) is deprecated. Instead, use the corresponding region-based time zone IDs listed in [ZoneId.SHORT_IDS](https://docs.oracle.com/en/java/javase/24/docs/api/java.base/java/time/ZoneId.html#SHORT_IDS).