@Entity
@Table(name = "TANNANN")
@Inheritance(strategy = InheritanceType.JOINED)
public class Advice {
...
}

@MappedSuperclass
public class RLAdvice extends Advice {

    private Counterparty clearer;
   @OneToOne(optional = false, fetch = FetchType.LAZY)
    @JoinColumn(name = "")
    public Counterparty getClearer() {
        return clearer;
    }
...
}

@Entity
@Table(name = "TSNPANN")
@PrimaryKeyJoinColumn(name = "IDXANN")
@AttributeOverrides(...)
@AssociationOverrides({
    @AssociationOverride(name = "clearer", joinColumns = @JoinColumn(name = "CLEARER")),
...
})
public class SnpAdvice extends RLAdvice {
...
}

@JoinColumn(name = "")

org.hibernate.AnnotationException: Illegal attempt to define a @JoinColumn with a mappedBy association: clearer
   at org.hibernate.cfg.Ejb3JoinColumn.buildJoinColumn(Ejb3JoinColumn.java:152)
   at org.hibernate.cfg.Ejb3JoinColumn.buildJoinColumns(Ejb3JoinColumn.java:127)
   at org.hibernate.cfg.AnnotationBinder.processElementAnnotations(AnnotationBinder.java:1094)
   at org.hibernate.cfg.AnnotationBinder.bindClass(AnnotationBinder.java:699)
   at org.hibernate.cfg.AnnotationConfiguration.processArtifactsOfType(AnnotationConfiguration.java:353)
   at org.hibernate.cfg.AnnotationConfiguration.secondPassCompile(AnnotationConfiguration.java:265)
   at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1205)