I don't know if this issue exists in other environments, but it can be consistently reproduced in the GNOME environment.
Steps to Reproduce:
- Run
GuiDemo or OsThemeDetectorDemo
- Observe the spawned processes

- Close the GUI window or terminate the demo
- Check whether the processes observed in step 2 have terminated

Expected Result:
All processes observed in step 2 should terminate.
Observed Result:
The gsettings process does not terminate. Each time the demo is run, a new gsettings process is created.
JDK:
liberica-full-11.0.27
OS:
Arch Linux