RFR: 8367981: Update CompactHashtable comments [v3]

[Hamlin Li]

> Hi,
> Can you help to review this patch?
> 
> The comments of CompactHashtable and related classes are out of date, and some comments are unclear, wrong or misleading.
> As the related classes are used in more and more scenarios, it's helpful to update the comments.
> 
> Thanks

Hamlin Li has updated the pull request incrementally with one additional commit since the last revision:

  refine comments; rename from _value to _encoded_value

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/27360/files
  - new: https://git.openjdk.org/jdk/pull/27360/files/176fdc67..9d3ad1ec

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27360&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27360&range=01-02

  Stats: 42 lines in 1 file changed: 15 ins; 3 del; 24 mod
  Patch: https://git.openjdk.org/jdk/pull/27360.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27360/head:pull/27360

PR: https://git.openjdk.org/jdk/pull/27360