[jdk17u-dev] RFR: 8365086: CookieStore.getURIs() and get(URI) should return an immutable List

[Goetz Lindenmaier]

I backport this for parity with 17.0.18-oracle,

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Commit messages:
 - Backport 022e29a77533aacabd56820d00ecffa9646a8362

Changes: https://git.openjdk.org/jdk17u-dev/pull/4080/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=4080&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8365086
  Stats: 127 lines in 2 files changed: 119 ins; 4 del; 4 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/4080.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/4080/head:pull/4080

PR: https://git.openjdk.org/jdk17u-dev/pull/4080