Surefire plugin hangs after upgrade to spring-boot-starter-parent 3.5.5: (non-)demon threads?

[fudimangoeggi]

We've just upgraded our project from spring-boot-starter-parent 3.5.4 to 3.5.5.

While there are no failing tests nor before nor after the upgrade, after the upgrade the surefire plugin hangs for 30 seconds after the tests:
[ERROR] Surefire is going to kill self fork JVM. The exit has elapsed 30 seconds after System.exit(0).
Could this be due to some non-demon thread that has been spawned by spring?

[bclozel]

We didn't get any report about this recently in Spring Boot. Besides, this issue has been created on the Spring Framework issue tracker. If you can provide a minimal sample application that reproduces the problem, please create a new issue on the Spring Boot tracker.
Thanks!