public Collection<String> getAllShadowTableNames() {
        return shadowTableRules.keySet();
    }
@Test
    void assertGetAllShadowTableNames() {
        Collection<String> allShadowTableNames = shadowRule.getAllShadowTableNames();
        assertThat(allShadowTableNames.size(), is(2));
        Iterator<String> iterator = allShadowTableNames.iterator();
        assertThat(iterator.next(), is("t_user"));
        assertThat(iterator.next(), is("t_order"));
    }