RFR: 8311585: Add JRadioButtonMenuItem to bug8031573.java [v6]

[Rajat Mahajan]

> I have made the test changes to include radio button in menu and tested the same and it works fine.

Rajat Mahajan has updated the pull request incrementally with one additional commit since the last revision:

  Update instructions for clarity

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Changes:
  - all: https://git.openjdk.org/jdk/pull/15441/files
  - new: https://git.openjdk.org/jdk/pull/15441/files/767f57ed..5944fe0d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15441&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15441&range=04-05

  Stats: 14 lines in 1 file changed: 3 ins; 0 del; 11 mod
  Patch: https://git.openjdk.org/jdk/pull/15441.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15441/head:pull/15441

PR: https://git.openjdk.org/jdk/pull/15441