RFR: 8328821: Map.of() derived view collection mutators should throw UnsupportedOperationException [v12]

[Liam Miller-Cushon]

> This change overrides mutator methods in the implementation returned by `Map.of().entrySet()` to throw `UnsupportedOperationException`.

Liam Miller-Cushon has updated the pull request incrementally with one additional commit since the last revision:

  Update for Stable Values

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Changes:
  - all: https://git.openjdk.org/jdk/pull/18522/files
  - new: https://git.openjdk.org/jdk/pull/18522/files/785f728d..264a7b08

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18522&range=11
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18522&range=10-11

  Stats: 33 lines in 2 files changed: 32 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/18522.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18522/head:pull/18522

PR: https://git.openjdk.org/jdk/pull/18522