@HighFrequencyInvocation
    public Optional<ShardingSphereUser> findUser(final Grantee grantee) {
        return configuration.getUsers().stream().filter(each -> each.getGrantee().accept(grantee)).findFirst();
    }
@Test
    void assertFindUser() {
        AuthorityRule rule = createAuthorityRule();
        Optional<ShardingSphereUser> actual = rule.findUser(new Grantee("admin", "localhost"));
        assertTrue(actual.isPresent());
        assertThat(actual.get().getGrantee().getUsername(), is("admin"));
        assertThat(actual.get().getGrantee().getHostname(), is("localhost"));
    }