RFR: 8364213: (bf) Improve java/nio/Buffer/GetChars.java test comments [v2]

[Brett Okken]

> Address code review comments which came in post integration/merge of https://github.com/openjdk/jdk/pull/26282.
> 
> Update/clarify test summary tag
> Document the values generated for arguments
> Move the endian-ness qualifier in the test descriptor string to not be first
> Change test method names to more closely match arg names of method under test

Brett Okken has updated the pull request incrementally with two additional commits since the last revision:

 - whitespace
 - better documentation for "random" test cases
   
   fix for random range generation (JDK-8364345)

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/26512/files
  - new: https://git.openjdk.org/jdk/pull/26512/files/42334abf..36b6bae7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=26512&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=26512&range=00-01

  Stats: 44 lines in 1 file changed: 41 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/26512.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26512/head:pull/26512

PR: https://git.openjdk.org/jdk/pull/26512