I have following class as superclass 

```
@Entity
@MappedSuperclass
public class Location implements LocationCapable {

    @Basic
    private Double latitude;

    @Basic
    private Double longitude;

    @Basic
    private List<String> geocells;

    @PrePersist
    @Transient
    private void generateGeoCells() {
        geocells = GeocellManager.generateGeoCell(getLocation());
    }

    public Double getLongitude() {
        return longitude;
    }

    public void setLongitude(Double longitude) {
        this.longitude = longitude;
    }

    public Double getLatitude() {
        return latitude;
    }

    public void setLatitude(Double latitude) {
        this.latitude = latitude;
    }

    @Override
    @Transient
    @JsonIgnore
    public Point getLocation() {
        return new Point(latitude, longitude);
    }

    @Override
    @Transient
    @JsonIgnore
    public String getKeyString() {
        return latitude + ":" + longitude;
    }

    @Override
    public List<String> getGeocells() {
        return geocells;
    }

    public void setGeocells(List<String> geocells) {
        this.geocells = geocells;
    }

}

```

And another one which inherits from this

But when I try to run JUnit test I got this

```
Caused by: org.datanucleus.metadata.InvalidMetaDataException: Class Location has application-identity and no objectid-class specified yet has 0 primary key fields. Unable to use SingleFieldIdentity.
at org.datanucleus.metadata.AbstractClassMetaData.determineObjectIdClass(AbstractClassMetaData.java:1032)
at org.datanucleus.metadata.ClassMetaData.populate(ClassMetaData.java:205)
at org.datanucleus.metadata.AbstractClassMetaData.validateSuperClass(AbstractClassMetaData.java:720)
at org.datanucleus.metadata.AbstractClassMetaData.determineSuperClassName(AbstractClassMetaData.java:642)
at org.datanucleus.metadata.ClassMetaData.populate(ClassMetaData.java:193)
at org.datanucleus.metadata.MetaDataManager$1.run(MetaDataManager.java:2317)
at java.security.AccessController.doPrivileged(Native Method)
at org.datanucleus.metadata.MetaDataManager.populateAbstractClassMetaData(MetaDataManager.java:2311)
at org.datanucleus.metadata.MetaDataManager.populateFileMetaData(MetaDataManager.java:2148)
at org.datanucleus.metadata.MetaDataManager.initialiseFileMetaDataForUse(MetaDataManager.java:864)
at org.datanucleus.metadata.MetaDataManager.loadPersistenceUnit(MetaDataManager.java:794)
at org.datanucleus.jpa.EntityManagerFactoryImpl.initialisePMF(EntityManagerFactoryImpl.java:488)
at org.datanucleus.jpa.EntityManagerFactoryImpl.<init>(EntityManagerFactoryImpl.java:355)
at org.datanucleus.store.appengine.jpa.DatastoreEntityManagerFactory.<init>(DatastoreEntityManagerFactory.java:63)
at org.datanucleus.store.appengine.jpa.DatastorePersistenceProvider.createEntityManagerFactory(DatastorePersistenceProvider.java:35)
at javax.persistence.Persistence.createFactory(Persistence.java:172)
... 67 more

```

Also I've tried to add in supperclass the key field annotated with @Id but it gives no result for me