JavaTest 4.1.3 prints the following exception stack trace to the console each time before shutting down when the JCK 6b b21 is running in the batch mode:

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Exception in thread "Thread-3" java.lang.IllegalStateException: Shutdown in progress
at java.lang.ApplicationShutdownHooks.remove(ApplicationShutdownHooks.java:55)
at java.lang.Runtime.removeShutdownHook(Runtime.java:220)
at com.sun.javatest.TestResultCache.shutdown(TestResultCache.java:451)
at com.sun.javatest.TestResultCache$2.run(TestResultCache.java:153)
starting cleanup
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To reproduce the problem, run any of JCK-runtime-6b b21 tests in the batch mode.

Note: the problem is not observable in the JCK running JavaTest 4.1.2.