DeployedJarTest.throwsIfFileIsNotValidJarFile() test failed in Windows CI https://concourse.apachegeode-ci.info/teams/main/pipelines/apache-develop-main/jobs/WindowsUnitTestOpenJDK11/builds/225
The problem did not reproduce on macOS in 1000 runs.
I notice that the JavaCompiler constructor calls the deprecated Files.createTempDir(). I wonder if there might be a race condition where two test processes (at once) think they own that temp dir and so they can both delete it.
We might consider replacing that deprecated call with the recommended Files.createTempDirectory() which may be more robust. Looking at the deprecated method and the recommended substitute the latter might have less of a chance of collision due to its use of random suffixes (versus the former's monotonically-increasing ints).