Java – How to implement a Spring Data repository for a @MappedSuperclass

I've got a JPA @MappedSuperClass and an @Entity extending it:

@MappedSuperclass
public class BaseClass {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @Column
    private Boolean active;

    //getters & setters

}

@Entity
public class Worker extends BaseClass{

    @Column
    private String name;

    //getters & setters

}

The active field of the base class is a flag for the children entities. Only the active ones should be loaded in the application. Then I've written a generic Spring Data Proxy interface:

public interface Dao<T extends BaseClass, E extends Serializable> extends
        CrudRepository<T, E> {

    Iterable<T> findByActive(Boolean active);

}

And this one is the interface that should be for Worker data access, properly extending the previous one:

@Transactional
public interface WorkerDao extends Dao<Worker, Long>{}

Well, now in my logic layer I've implemented an abstract class which will wrap the common code for CRUD operations over my entities. I'll have a service for each of them, but I want just to inherit from the abstract one. I want to wire the specific repository for each of the services and provide it to the superclass using an abstract method. That's how my superclass is implemented:

public abstract class GenericService<E extends BaseClass>{

    public abstract Dao<E, Long> getDao();

    //Here I've got some common operations for managing 
    //all my application classes, including Worker

}

The problem is that the getDao() method uses the E class parameter, which is guaranteed only to be a child of BaseClass and not a javax.persistence.Entity. When I try to access the DAO from my custom service implementation I get this error:

Caused by: java.lang.IllegalArgumentException: Could not create query metamodel for method public abstract java.lang.Iterable com.mycompany.model.daos.interfaces.Dao.findByActive(java.lang.Boolean)!
at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$CreateQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:93)

Caused by: java.lang.IllegalArgumentException: Not an entity: class com.mycompany.model.BaseClass
at org.hibernate.jpa.internal.metamodel.MetamodelImpl.entity(MetamodelImpl.java:203)

Which makes sense, because E is defined as a child of BaseClass. The compiler allows me to write this too:

public abstract class GenericService<E extends BaseClass && Entity>

However I get an error in the child Service that says Worker class is not compatible with the signature for E. Does anybody know how to solve this?