@Override
    public void update(List<V> values) {
        throw MODIFICATION_ATTEMPT_ERROR;
    }
@Test
    void testUpdate() throws Exception {
        List<Long> list = getStateContents();
        assertThat(list).containsExactly(42L);
        assertThatThrownBy(() -> listState.add(54L))
                .isInstanceOf(UnsupportedOperationException.class);
    }