RFR: 8308694: Clarify reversed() default methods' implementation requirements [v3]

[Stuart Marks]

> Can I get a preliminary review of the wording for Deque.reversed()? If the text is good, I'll make corresponding changes to the implSpecs of the other reversed() default methods, namely those in List, SortedMap, and SortedSet and then file the CSR.

Stuart Marks has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - Merge branch 'master' into JDK-8308694-clarify-reversed
 - Update to avoid overspecification.
 - 8308694: Clarify reversed() default methods' implementation requirements

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/14504/files
  - new: https://git.openjdk.org/jdk/pull/14504/files/0a8b769f..c8a69ee7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14504&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14504&range=01-02

  Stats: 74794 lines in 1515 files changed: 18072 ins; 48133 del; 8589 mod
  Patch: https://git.openjdk.org/jdk/pull/14504.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14504/head:pull/14504

PR: https://git.openjdk.org/jdk/pull/14504