[jdk26] RFR: 8376169: JPopupMenu.setInvoker(null) causes NPE

[Prasanta Sadhukhan]

8376169: JPopupMenu.setInvoker(null) causes NPE

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Commit messages:
 - Backport 2529e2fe8dfe9685033bb0ae558266b8bc3cf95c

Changes: https://git.openjdk.org/jdk/pull/29477/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29477&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8376169
  Stats: 14 lines in 2 files changed: 10 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/29477.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29477/head:pull/29477

PR: https://git.openjdk.org/jdk/pull/29477