Criteria API query involving collection AttributeConverter stopped working in Hibernate ORM 6.3

Hello,

after migrating from Hibernate ORM 6.2.13 to 6.3.1 I noticed, that Criteria API queries involving column with AttributeConverter<List, String> stopped working.

class StringListConverter implements AttributeConverter<List<String>, String> {
    @Override
    public String convertToDatabaseColumn(List<String> elements) {
        return elements == null || elements.isEmpty() ? null : String.join(",", elements);
    }

    @Override
    public List<String> convertToEntityAttribute(String dbData) {
        return dbData == null ? null : List.of(dbData.split(","));
    }
}
@Entity
public class Employee {
    @Id
    private Long id;

    @Convert(converter = StringListConverter.class)
    private List<String> phoneNumbers;
}

JPQL query works fine with Hibernate 6.2.* and also 6.3.0, 6.3.1.

List<String> phoneNumbers = (List<String>) em
    .createQuery("select emp.phoneNumbers from Employee emp where emp.id = :EMP_ID")
    .setParameter("EMP_ID", 1)
    .getSingleResult();

// OK - it is as expected ["0911 111 222", "0922 222 222"]
System.out.println("phoneNumbers = " + phoneNumbers);

Equivalent JPA Criteria API query worked in versions Hibernate 6.2.* but does not work in 6.3.*

CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<List> q = cb.createQuery(List.class);
Root<Employee> r = q.from(Employee.class);
q.select(r.get(Employee_.phoneNumbers));
q.where(cb.equal(r.get(Employee_.id), 1);
List<String> phoneNumbers = em.createQuery(q).getSingleResult();

// WRONG - it is [["0911 111 222", "0922 222 222"]] but should be ["0911 111 222", "0922 222 222"]
System.out.println("phoneNumbers = " + phoneNumbers);

It seems that Hibernate 6.3 wraps value of type List into an additinal List, and that IMHO is wrong.

Please try to create a reproducer with our test case template (https://github.com/hibernate/hibernate-test-case-templates/blob/master/orm/hibernate-orm-6/src/test/java/org/hibernate/bugs/JPAUnitTestCase.java) and if you are able to reproduce the issue, create a bug ticket in our issue tracker(https://hibernate.atlassian.net) and attach that reproducer.

A reproducer is now available here https://github.com/brinvex/hibernate-test-case-templates/blob/1176112744c2010ffd9866ca021843710d97283b/orm/hibernate-orm-6/src/test/java/org/hibernate/bugs/JPAUnitTestCase.java
The bug ticket is here [HHH-17393] - Hibernate JIRA.