Hibernate: Is it possible to map multi-level inheritance to single table?

Question

I have following inheritance hierarchy:

Task
  |
SpecificTask
  |
VerySpecificTask

And I'd like to persist it usign single-table inheritance, so I annotated classes:

@Entity
@Table(name="task")
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
public class Task 

@Entity
public class SpecificTask extends Task 

@Entity
public class VerySpecificTask extends SpecificTask

When I try to save an object of VerySpecificTask class, I get an error:

Unable to resolve entity name from Class [com.application.task.VerySpecificTask] 
expected instance/subclass of [com.application.task.Task]

What do I wrong? Is it possible to map multi-level inheritance to single table?

EDIT: Here was a lame bug, I've resolved quickly, so I deleted it to not mess this question.

Answer 1

OK, I've added discriminator column and now it works. Changed code:

@Entity
@Table(name="task")
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(
        name="DTYPE",
        discriminatorType=DiscriminatorType.STRING
    )

@Entity
public class SpecificTask extends Task 

@Entity
public class VerySpecificTask extends SpecificTask

(I'm adding it just to provide an accepted answer -- I wouldn't resolve it without the helpful comments to the question.)

Answer 2

The accepted answer is almost perfect. To make it more clear I want to add a @DiscriminatorValue to each inheritance level.

@Entity
@Table(name="task")
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(
        name="DTYPE",
        discriminatorType=DiscriminatorType.STRING
)
public class Task

---

@Entity
@DiscriminatorValue(value="DS")
public class SpecificTask extends Task 

---

@Entity
@DiscriminatorValue(value="DV")
public class VerySpecificTask extends SpecificTask

And the materiliazed table looks like

--------------- 
Table: task
---------------
|...|DTYPE|...|
---------------
|...|DS   |...|
|...|DV   |...|
|...|DS   |...|
...