Suppose an entity model where an `Employee` has a `Supervisor` who has an `id`. Using `hibernate-jpamodelgen` to generate the meta model for the entities, how can I query a nested field?

For instance, "get all employees whose supervisor has id 4", using `JpaSpecificationExecutor`:

```java
Page<Employee> getEmployeesBySupervisorId(int id) {
  return findAll((root, query, criteriaBuilder) -> {
    return criteriaBuilder.equal(root.get(Employee_.supervisor.id), id);
  });
}

```

Note that `Employee_` is the model meta class for `Employee` (and was generated by Hibernate).

This code will produce an error because the `id` symbol cannot be found on type `SingularAttribute<Employee, Supervisor>`. I get that, but it seems like these should somehow be chainable. I can't find great examples of how to do this cleanly.