RFR: 8324342: Doclet should default @since for a nested class to that of its enclosing class [v2]

[Jonathan Gibbons]

> Please review changes to the support for `since`, `author`, and `version` tags, such that if there are no such tags on a nested class, the doclet will look for any such tags in enclosing classes.

Jonathan Gibbons has updated the pull request incrementally with one additional commit since the last revision:

  add more test cases

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Changes:
  - all: https://git.openjdk.org/jdk/pull/18407/files
  - new: https://git.openjdk.org/jdk/pull/18407/files/7a1dc75c..c7318a59

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18407&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18407&range=00-01

  Stats: 101 lines in 2 files changed: 101 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/18407.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18407/head:pull/18407

PR: https://git.openjdk.org/jdk/pull/18407