First of all, I apologise in advance if this is the not right place to report this bug.

I encounter this error after upgrading to hibernate 6 but, based on my findings, it occurs only with Kotlin (it works properly in Java).

I decided to open a ticket here because it works properly with Hibernate version 5.x

Context

I have this table

CREATE TABLE vehicles (
    id uuid DEFAULT random_uuid(),
    vehicle_type varchar(255) not null,
    brand varchar(255) not null
);
insert into vehicles (vehicle_type, brand) values ('CAR', 'Audi')

and defined two entities with SINGLE_TABLE hierarchy:

@Entity
@Table(name = "vehicles")
@DiscriminatorColumn(name = "vehicle_type", discriminatorType = DiscriminatorType.STRING)
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
abstract class VehicleKotlin(
    @Id
    open var id: UUID,
    @Column(name = "brand")
    open var brand: String,
)

@Entity
@DiscriminatorValue("CAR")
data class CarKotlin(
    @Id override var id: UUID,
    override var brand: String,
) : VehicleKotlin(
    id = id,
    brand = brand,
)

Error

When I try to query the database

FROM VehicleKotlin WHERE brand =’s

it seems like that the serialization does not work work properly.

As you can see in the attachment, id and brand are null while VehicleKotlin.id` and`VehicleKotlin.brand` are set with the right values (but they don’t even exist in the model).

In this demo (https://github.com/detomarco/hibernate-bug-report ) you can find the same code work properly in Java but not in Koltin.

Thank you in advance