RFR: CODETOOLS-7903346: Cannot compile jtreg with jdk-19

Thu Oct 6 00:10:56 UTC 2022

Please review a trivial change to a class in the jtreg repo, to disable warnings on an "unintentionally serializable" class.
The class extends `TreeMap` which happens to be `Serializable`, and the class contains some non-serializable fields.

In JDK 18, the javac serialization warnings were enhanced, causing this code to fail to compile with `-Xlint -Werror`.

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Commit messages:
 - CODETOOLS-7903346: Cannot compile jtreg with jdk-19

Changes: https://git.openjdk.org/jtreg/pull/129/files
 Webrev: https://webrevs.openjdk.org/?repo=jtreg&pr=129&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903346
  Stats: 3 lines in 1 file changed: 1 ins; 2 del; 0 mod
  Patch: https://git.openjdk.org/jtreg/pull/129.diff
  Fetch: git fetch https://git.openjdk.org/jtreg pull/129/head:pull/129

PR: https://git.openjdk.org/jtreg/pull/129