There are two sets of localized resources in the current JDK, i.e., CLDR based one and the legacy COMPAT one. Removing the COMPAT will reduce the footprint, as well as the startup time. Here are a few things to take into account:

- BreakIterator/Collator: these are not provided by the CLDR locale provider. The existing FALLBACK provider (internal implementation) will be re-purposed to support these functions.

- Display names for time zones have some dependency on COMPAT, which may affect the CLDRConverter that generates names.
    - Old three-letter abbreviations
    - CLDR aliases deprecated zones such as `SystemV/YST9` -> `Pacific/Gambier`
    - metaZones aliases inconsistency, e.g., Casablanca started negative dst in 2018, thus differs from Western Europe Time.

- SimpleDateFormat with Japanese Calendar: No "Gan-nen" resources are in CLDR. The FALLBACK provider will need to support it.

By removing `COMPAT` provider, specifying it with `java.locale.providers` system property will have no effect, as if `COMPAT` did not exist in the vallue.