public static Thread daemonThread(Runnable r, Class<?> context, String description) {
        return daemonThread(r, "hollow", context, description);
    }
@Test
    public void nullName() {
        try {
            daemonThread(() -> {}, null);
            fail("expected an exception");
        } catch (NullPointerException e) {
            assertEquals("name required", e.getMessage());
        }
    }