RFR: 8376169: JPopupMenu.setInvoker(null) causes NPE [v4]

[Prasanta Sadhukhan]

> Invoking `JPopupMenu.setInvoker(null)` causes NPE which is fixed in this PR

Prasanta Sadhukhan has updated the pull request incrementally with one additional commit since the last revision:

  Test update

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/29377/files
  - new: https://git.openjdk.org/jdk/pull/29377/files/91151bce..b588d51d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=29377&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=29377&range=02-03

  Stats: 8 lines in 2 files changed: 7 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/29377.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29377/head:pull/29377

PR: https://git.openjdk.org/jdk/pull/29377