RFR: CODETOOLS-7903302: cleanup code [v3]

[Jonathan Gibbons]

> Please review a medium-sized update to clean up the jtreg code.
> 
> Most of the changes were performed directly by the IDE. Many of the changes are very local (same line) but some affect surrounding lines when the code was reformatted ... for example, when using lambdas, or try with resources.
> 
> The most "risky" change was converting `Arrays.asList`, which permits `null`, to `List.of`, which does not. This was fixed up manually in a few places, most notable in `ModuleConfig`. In all places, `null` was easily changed to an empty string `""`.

Jonathan Gibbons has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains three commits:

 - merge with upstream/master
 - merge with upstream/master
 - CODETOOLS-7903302: cleanup code

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

Changes: https://git.openjdk.org/jtreg/pull/118/files
 Webrev: https://webrevs.openjdk.org/?repo=jtreg&pr=118&range=02
  Stats: 517 lines in 30 files changed: 12 ins; 258 del; 247 mod
  Patch: https://git.openjdk.org/jtreg/pull/118.diff
  Fetch: git fetch https://git.openjdk.org/jtreg pull/118/head:pull/118

PR: https://git.openjdk.org/jtreg/pull/118