<i18n dev> RFR: 8348351: Improve lazy initialization of the available currencies set

Thu May 8 23:00:26 UTC 2025

Please review this PR which stems from discussion in the PR of JDK-8347949.

The set of lazily loaded Currencies is a good fit for stable values. `available` can now be made final as it is a SV supplier.

(This change also includes an unrelated minor edit to comments in `Currency::getCurrencies` to make the distinction for simple vs special Currencies.)

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Commit messages:
 - init

Changes: https://git.openjdk.org/jdk/pull/25134/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25134&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8348351
  Stats: 46 lines in 1 file changed: 3 ins; 2 del; 41 mod
  Patch: https://git.openjdk.org/jdk/pull/25134.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25134/head:pull/25134

PR: https://git.openjdk.org/jdk/pull/25134