    @Test
    void tesExNull() {

        int[] counter = {0};
        CloseableThrowableSupplier<String, RuntimeException> supplier = lazyEx(() -> {
            counter[0]++;
            return null;
        });
        assertNull(supplier.get());
        assertNull(supplier.get());
        assertEquals(counter[0], 1);
        supplier.tryClose();
        assertNull(supplier.get());
        assertNull(supplier.get());
        assertEquals(counter[0], 2);
    }