RFR: 8174840: Elements.overrides does not check the return type of the methods [v3]

[Pavel Rappo]

> Please review this essentially doc only change.

Pavel Rappo has updated the pull request incrementally with one additional commit since the last revision:

  Improve characterisation testcases

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Changes:
  - all: https://git.openjdk.org/jdk/pull/22244/files
  - new: https://git.openjdk.org/jdk/pull/22244/files/a9a4309b..add209c4

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22244&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22244&range=01-02

  Stats: 12 lines in 2 files changed: 10 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/22244.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22244/head:pull/22244

PR: https://git.openjdk.org/jdk/pull/22244