ConfigurationTest.java creates directories and files in the default temp directory, but does not clean up later.

cat -n jdk/test/java/lang/module/ConfigurationTest.java
   [...]
  2120 Path dir = Files.createTempDirectory(name);


The preferred approach would be to create temporary test files and directories under the jtreg property user.dir instead, if it is defined.

During a jtreg run, user.dir has the value $PWD/JTwork/scratch