How to unit test ldap template search method?

Question

I am writing ldap query to search username from email and the method is this

    final ContainerCriteria query = ldapQuery(email);


        var attr = (AttributesMapper<String>) attrs -> attrs
                            .get("uid")
                            .get()
                            .toString()

LdapQueryBuilder
                .query()
                .where("objectclass")
                .is("person")
                .and("mail")
                .is(email);

ldapTemplate.search(query, attr);

I need to unit test this method but since there is no equals method on AttributesMapper and ContainerCriteria I

@Test
    public void shouldReturnUsername() {
        final List<String> user = Arrays.asList("shahg");

        final ContainerCriteria containerCriteria = LdapQueryBuilder
                .query()
                .where("objectclass")
                .is("person")
                .and("mail")
                .is("[email protected]");

                var attr = (AttributesMapper<String>) attrs -> attrs
                            .get("uid")
                            .get()
                            .toString()

        when(dapTemplate
                .search(containerCriteria, (AttributesMapper<String>) attrs -> attrs
                        .get("uid")
                        .get()
                        .toString()));

        ldapService.getUsername("[email protected]");

}

Even though everything is same, test fails. I tried with ArgumentMatcher as well but the same result.