RFR: 8341903: Implementation of Scoped Values (Fourth Preview) [v2]

[Andrew Haley]

> The fourth preview of scoped values.

Andrew Haley has updated the pull request incrementally with one additional commit since the last revision:

  Fix javadoc

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Changes:
  - all: https://git.openjdk.org/jdk/pull/21456/files
  - new: https://git.openjdk.org/jdk/pull/21456/files/77e055b6..0d178006

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21456&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21456&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/21456.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21456/head:pull/21456

PR: https://git.openjdk.org/jdk/pull/21456