// Test documentSize
        assertEquals(0L, indexUpdater.getDocumentSize());
    }

    // Test setUncaughtExceptionHandler
    @Test
    public void test_setUncaughtExceptionHandler() {
        final AtomicBoolean handlerCalled = new AtomicBoolean(false);
        final Thread.UncaughtExceptionHandler handler = (t, e) -> handlerCalled.set(true);