Some tests catch Exceptions in separate threads and just print a stack trace - the test does not fail. The test should fail. Since
LUCENE-2274, the LuceneTestCase(J4) class installs an UncaughtExceptionHandler, so this type of catching and solely printing a Stack trace is a bad idea. Problem is, that the run() method of threads is not allowed to throw checked Exceptions.
- Catch checked Exceptions in the run() method and wrap into RuntimeException or call Assert.fail() instead
- Use Executors