Missing value provider - Hibernate upgrade

[Puckoland]

While upgrading Hibernate, I encountered this issue:
ValueProviderTest::testDeletion() (and other tests) fails on creating AliasProvider.

The issue lies in ValueProvider::modifyFromApi().
It gets ValueProviderCapability from the resource, but the ValueProviderCapability has not set ValueProvider (it is null).

However, when the ValueProviderCapability has been created, it did have ValueProvider.
Also, I tried Joining the entities with a query which returned (1, 2, 2, 1).

SELECT valCap.id, valCap.value_provider_id, vp.id, vp.capability_id FROM resource r" +
                            " JOIN capability c ON c.resource_id = r.id" +
                            " JOIN value_provider_capability valCap ON valCap.id = c.id" +
                            " JOIN value_provider vp ON valCap.value_provider_id = vp.id" +
                            " WHERE r.id = :resourceId

This is why I suspect that Hibernate is not correctly mapping the entities together.

---

I think that the issue might be in the mappings:

@Entity
public class ValueProviderCapability extends Capability
    @OneToOne(cascade = CascadeType.ALL)
    @Access(AccessType.FIELD)
    public ValueProvider getValueProvider() { return valueProvider; }
}

@Entity
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
public abstract class ValueProvider extends SimplePersistentObject {
    @ManyToOne
    @Access(AccessType.FIELD)
    public Capability getCapability() { return capability; }
}

---

Also, I find the resulting relationship peculiar. value_provider holds capability_id, and value_provider_capability holds value_provider_id. It seems to me like a bidirectional relationship.

TABLE value_provider

dtype	id	type	allow_any_requested_value	capability_id	value_provider_id
PatternValueProvider	33		t	32
PatternValueProvider	59		f	58
FilteredValueProvider	1252	CONVERT_TO_URL	f	1251	33

TABLE value_provider_capability

id	value_provider_id
32	33

[Puckoland]

Also, it might be important that there is one more Capability subclass called AliasProviderCapability using ValueProvider that can be the same as the one mapped to ValueProviderCapability (or another AliasProviderCapability).
There are also other Capability subclasses that do not (so valueProvider reference cannot be moved to the Capability class).

@Entity
public class AliasProviderCapability extends Capability
    @ManyToOne(cascade = CascadeType.ALL)
    @Access(AccessType.FIELD)
    public ValueProvider getValueProvider() { return valueProvider; }
}