After switch the run to concurrency mode, observe this test fails intermittently with:

----------System.out:(1/20)----------
-- test shutdown --
----------System.err:(15/756)----------
java.lang.RuntimeException: Group should have terminated
	at Basic.awaitTermination(Basic.java:52)
	at Basic.testShutdownWithNoChannels(Basic.java:63)
	at Basic.shutdownTests(Basic.java:107)
	at Basic.main(Basic.java:43)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:502)
	at com.sun.javatest.regtest.agent.MainActionHelper$SameVMRunnable.run(MainActionHelper.java:218)
	at java.lang.Thread.run(Thread.java:745)

Failed at:

    static void awaitTermination(AsynchronousChannelGroup group) throws InterruptedException {
        boolean terminated = group.awaitTermination(20, TimeUnit.SECONDS);
        if (!terminated)
            throw new RuntimeException("Group should have terminated");
    }