RFR: 8315761: Open source few swing JList and JMenuBar tests [v2]

[Abhishek Kumar]

> Few closed JList and JMenubar swing tests are open sourced.

Abhishek Kumar has updated the pull request incrementally with one additional commit since the last revision:

  Review comment update

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Changes:
  - all: https://git.openjdk.org/jdk/pull/15621/files
  - new: https://git.openjdk.org/jdk/pull/15621/files/cf4fe6c5..90d33005

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15621&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15621&range=00-01

  Stats: 7 lines in 1 file changed: 3 ins; 4 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/15621.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15621/head:pull/15621

PR: https://git.openjdk.org/jdk/pull/15621