RFR: 8336043: Add quality of implementation discussion to Object.{equals, toString, hashCode} [v3]

[Joe Darcy]

> First pass at adding some quality of implementation discussions around the overridable methods of Object.

Joe Darcy has updated the pull request incrementally with one additional commit since the last revision:

  Respond to review feedback.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/20128/files
  - new: https://git.openjdk.org/jdk/pull/20128/files/81245907..95f890bf

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20128&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20128&range=01-02

  Stats: 14 lines in 1 file changed: 5 ins; 0 del; 9 mod
  Patch: https://git.openjdk.org/jdk/pull/20128.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20128/head:pull/20128

PR: https://git.openjdk.org/jdk/pull/20128