@Override
    public void clear() {
        throw MODIFICATION_ATTEMPT_ERROR;
    }
@Test
    void testClear() throws Exception {
        assertThat(mapState.contains(1L)).isTrue();
        long value = mapState.get(1L);
        assertThat(value).isEqualTo(5L);

        assertThat(mapState.contains(2L)).isTrue();
        value = mapState.get(2L);
        assertThat(value).isEqualTo(5L);

        assertThatThrownBy(() -> mapState.clear())
                .isInstanceOf(UnsupportedOperationException.class);
    }