NullPointerException thrown to flash after upgrading to Hibernate 4.1.3 Final

I just finished upgrading from Hibernate 3.6 to 4.1.3 Final, and at first everything seemed fine. However, one of my colleagues recently tested this, and in one scenario, it gets NullPointer, which is thrown from Hibernate (and this exception was not thrown before we updated it for the same database). This is an incredibly strange scenario. We have an object called BlogPost that looks like below, and it extends some mapped superclasses (which I also included):

@Entity
@Table(name = "blog_post")
public class BlogPost extends CommunityModelObject implements HasFeedPost {

    @Lob
    private String title;
    @Lob
    private String content;
    @Enumerated
    @Column(nullable = false)
    private CBlogPost.Status status = CBlogPost.Status.UNPUBLISHED;
    // Reference to the feed post that indicates that this blog post has been published
    @OneToOne
    @JoinColumn(name = "feed_post_id")
    private FeedPost feedPost;
    @ManyToOne
    @JoinColumn(name = "posted_by_employee_id")
    private Employee postedBy;

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public CBlogPost.Status getStatus() {
        return status;
    }

    public void setStatus(CBlogPost.Status status) {
        this.status = status;
    }

    @Override
    public FeedPost getFeedPost() {
        return feedPost;
    }

    @Override
    public void setFeedPost(FeedPost feedPost) {
        this.feedPost = feedPost;
    }

    public Employee getPostedBy() {
        return postedBy;
    }

    public void setPostedBy(Employee postedBy) {
        this.postedBy = postedBy;
    }
}


@Filter(name = "tenantFilter", condition = "(tenant_id = :tenantId or tenant_id is null)")
@MappedSuperclass
public abstract class CommunityModelObject extends ModelObject {

    @IndexedEmbedded(prefix = "tenant", indexNullAs = IndexedEmbedded.DEFAULT_NULL_TOKEN)
    @ManyToOne
    @JoinColumn(name = "tenant_id")
    protected Tenant tenant;

    public Tenant getTenant() {
        return tenant;
    }

    public void setTenant(Tenant tenant) {
        this.tenant = tenant;
    }

    /**
     * If the Tenant is null then it can be accessed / viewed by the entire "community" / user base
     */
    public boolean isCommunityObject() {
        return tenant == null;
    }
}


@MappedSuperclass
public abstract class ModelObject extends BaseModelObject {

    @Id
    @GeneratedValue
    private Long id;

    @Override
    public long getId() {
        return (id == null ? 0 : id);
    }

    public void setId(long id) {
        this.id = (id == 0 ? null : id);
    }
}


@MappedSuperclass
public abstract class BaseModelObject implements java.io.Serializable {

    // This annotation ensures that a column is not associated with this member (simply omitting the @Column annotation is not enough since
    // that annotation is completely optional)
    @Transient
    private boolean doNotAutoUpdateDateUpdated = false;

    @Version
    protected int version;
    @Column(name = "date_created")
    protected Date dateCreated;
    @Column(name = "date_updated")
    protected Date dateUpdated;

    public abstract long getId();

    public int getVersion() {
        return version;
    }

    public void setVersion(int version) {
        this.version = version;
    }

    public Date getDateCreated() {
        return dateCreated;
    }

    public Date getDateUpdated() {
        return dateUpdated;
    }

    /**
     * This will set the dateUpdated to whatever is passed through and it will cause the auto update (pre-update) to NOT occur
     *
     * @param dateUpdated
     */
    public void setDateUpdated(Date dateUpdated) {
        doNotAutoUpdateDateUpdated = true;
        this.dateUpdated = dateUpdated;
    }

    public void touch() {
        // By setting date updated to null this triggers an update which results in onUpdate being called and the nett
        // result is dateUpdated = new Date()
        dateUpdated = null;
    }

    @PrePersist
    protected void onCreate() {
        dateCreated = new Date();
    }

    @PreUpdate
    protected void onUpdate() {
        if (!doNotAutoUpdateDateUpdated) {
            dateUpdated = new Date();
        }
    }

    @Override
    public boolean equals(Object obj) {
        long id = getId();

        if (id == 0) {
            return this == obj;
        }
        //Use Hibernate.getClass() because objects might be proxies
        return obj != null &&
                obj instanceof BaseModelObject &&
                Hibernate.getClass(this) == Hibernate.getClass(obj) &&
                getId() == ((BaseModelObject)obj).getId();
    }

    @Override
    public int hashCode() {
        Long id = getId();
        return id == 0 ? super.hashCode() : id.intValue();
    }

    @Override
    public String toString() {
        return getClass().getSimpleName() + "-" + getId();
    }
}

, BlogPost . , , , , , :

select b from BlogPost b

java.lang.NullPointerException
   at org.hibernate.event.internal.DefaultFlushEntityEventListener.isUpdateNecessary(DefaultFlushEntityEventListener.java:240)
   at org.hibernate.event.internal.DefaultFlushEntityEventListener.onFlushEntity(DefaultFlushEntityEventListener.java:163)
   at org.hibernate.event.internal.AbstractFlushingEventListener.flushEntities(AbstractFlushingEventListener.java:225)
   at org.hibernate.event.internal.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:99)
   at org.hibernate.event.internal.DefaultAutoFlushEventListener.onAutoFlush(DefaultAutoFlushEventListener.java:55)
   at org.hibernate.internal.SessionImpl.autoFlushIfRequired(SessionImpl.java:1153)
   at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1208)
   at org.hibernate.internal.QueryImpl.list(QueryImpl.java:101)
   at org.hibernate.ejb.QueryImpl.getResultList(QueryImpl.java:256)

, , , BlogPost BlogPost java.io.Serializable, . , , Hibernate, CommunityModelObject.

, ? , Hibernate, . , , Hibernate Search, .

, - MySQL , BIT:

public class MySQL5InnoDBDialectExt extends MySQL5InnoDBDialect {

    private static final String BIT_STRING = "bit";

    public MySQL5InnoDBDialectExt() {
        super();
        registerColumnType(Types.BOOLEAN, BIT_STRING);
    }
}

, Brent