RFR: 8361715: (bf) Improve java/nio/Buffer/GetChars.java and migrate to JUnit [v11]

[Brian Burkhalter]

On Fri, 25 Jul 2025 18:47:21 GMT, Brett Okken <duke at openjdk.org> wrote:

>> junit for CharSequence behavior of CharBuffer covering different CharBuffer implementations in various states (offset, position, limit)
>
> Brett Okken has updated the pull request incrementally with one additional commit since the last revision:
> 
>   code review comments

Looks good.

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Marked as reviewed by bpb (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/26282#pullrequestreview-3056758816