<i18n dev> RFR: 8167252: Some of Charset.availableCharsets() does not contain itself [v2]

[Naoto Sato]

> Adding themselves into their `contains()` method will fix it.

Naoto Sato has updated the pull request incrementally with one additional commit since the last revision:

  Refined the test

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Changes:
  - all: https://git.openjdk.org/jdk/pull/14473/files
  - new: https://git.openjdk.org/jdk/pull/14473/files/89899160..bea24165

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14473&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14473&range=00-01

  Stats: 5 lines in 1 file changed: 3 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/14473.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14473/head:pull/14473

PR: https://git.openjdk.org/jdk/pull/14473