RFR: CODETOOLS-7903302: cleanup code

Tue Sep 13 22:10:22 UTC 2022

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 `""`.

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Commit messages:
 - CODETOOLS-7903302: cleanup code

Changes: https://git.openjdk.org/jtreg/pull/118/files
 Webrev: https://webrevs.openjdk.org/?repo=jtreg&pr=118&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903302
  Stats: 523 lines in 31 files changed: 12 ins; 259 del; 252 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