RFR: 8361387 : Test bug4655513.java fails intermittently on Windows platform.

[Anass Baya]

This test was recently automated and is failing intermittently in the CI due to timing issues.
This enhancement aims to stabilize the test and also adds the missing null pointer check.

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Commit messages:
 - Test stabilization

Changes: https://git.openjdk.org/jdk/pull/26824/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26824&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8361387
  Stats: 8 lines in 1 file changed: 5 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/26824.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26824/head:pull/26824

PR: https://git.openjdk.org/jdk/pull/26824