RFR: 8340670: Policy.UNSUPPORTED_EMPTY_COLLECTION.isReadOnly does not return true [v2]

[Artur Barashev]

> https://bugs.openjdk.org/browse/JDK-8340670

Artur Barashev has updated the pull request incrementally with one additional commit since the last revision:

  Update copyright

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Changes:
  - all: https://git.openjdk.org/jdk/pull/21165/files
  - new: https://git.openjdk.org/jdk/pull/21165/files/9c80a004..2b1c9b03

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21165&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21165&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/21165.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21165/head:pull/21165

PR: https://git.openjdk.org/jdk/pull/21165