Hi, I'm having trouble adding a serializable array to my object. For the mapping document below, I get a NullPointerException in org.hibernate.type.IntegerType.next.
However, if I comment out the <property name="messages" .../>, then the object
appears to be persisted correctly (although the messages property is not
saved).

I'm trying to work this down to a test case; does anyone have any ideas?
Note I am using the Derby database, but so far I haven't had any other problems with it.

Hibernate version:
3.0.2

Mapping documents:
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping
package="org.gnome.yarrr">

<class name="ClosedComment">
<id name="referenceId" column="closedCommentReferenceId">
<generator class="native"/>
</id>
<version name="version" access="field" unsaved-value="null"/>
<many-to-one name="topic" access="field" column="topicId" not-null="true"/>
<property name="content" access="field" type="serializable" length="32000"/>
<many-to-one name="closer" access="field" class="Person" not-null="true"/>
<property name="openDate" access="field" not-null="true" type="timestamp"/>
<property name="closeDate" access="field" not-null="true" type="timestamp"/>
<property name="messages" lazy="true" access="field" type="serializable" length="32000"/>
<set name="proponents" access="field" cascade="all">
<key column="proponentid"/>
<many-to-many column="proponentpersonid" class="Person"/>
</set>
<set name="authors" access="field" cascade="all">
<key column="authorid"/>
<many-to-many column="authorpersonid" class="Person"/>
</set>
</class>
</hibernate-mapping>

Full stack trace of any exception that occurs:
java.lang.NullPointerException
at org.hibernate.type.IntegerType.next(IntegerType.java:57)
at org.hibernate.engine.Versioning.increment(Versioning.java:25)
at org.hibernate.event.def.DefaultFlushEntityEventListener.getNextVersion(DefaultFlushEntityEventListener.java:261)
at org.hibernate.event.def.DefaultFlushEntityEventListener.onFlushEntity(DefaultFlushEntityEventListener.java:139)
at org.hibernate.event.def.AbstractFlushingEventListener.flushEntities(AbstractFlushingEventListener.java:190)
at org.hibernate.event.def.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:70)
at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:26)
at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:678)
at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:309)
at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:86)
at org.gnome.yarrr.HibernateUtil.commitTransaction(HibernateUtil.java:169)
at org.gnome.yarrr.tests.YarrrTests.tearDown(YarrrTests.java:33)


Name and version of the database you are using:
Derby

I'm also including the code for the object in question:


/**
* @author walters
*/
public class ClosedComment extends ReferencableObject implements XmlRpcSerializable {
private Topic topic;
private YarrrMarkup content;
private Person closer;
private Date openDate;
private Date closeDate;
private Set /* Person */ proponents;
private Set /* Person */ authors;
private Integer version;
private SavedMessage[] messages;

protected class SavedMessage implements Serializable {
private static final long serialVersionUID = 1L;
private Date date;
private Person.Ref author;
private YarrrMarkup contents;
private Set /* Person.Ref */ subscribers;
private boolean byMe;

public SavedMessage() {}

public SavedMessage(ChatMessage mesg) {
this.date = mesg.getDate();
this.author = mesg.getAuthor();
this.contents = mesg.getContents();
this.subscribers = new HashSet(mesg.getSubscriberRefs());
this.byMe = mesg.isByMe();
}

public Person.Ref getAuthor() {
return author;
}
public boolean isByMe() {
return byMe;
}
public YarrrMarkup getContents() {
return contents;
}
public Date getDate() {
return date;
}
public Set getSubscribers() {
return subscribers;
}
}

private static Log logger = LogFactory.getLog(ClosedComment.class);

public static Set xmlRpcRemotableMethods = new HashSet();

ClosedComment() {}

public ClosedComment(Topic topic, Person closer, String content, Set /* Person */ authors, Date openDate, List /* ChatMessage */ messages) {
this.openDate = openDate;
this.topic = topic;
this.content = new YarrrMarkup(content);
this.closer = closer;
this.closeDate = new Date();
this.proponents = new HashSet();
this.authors = authors;
setMessages(messages);
HibernateUtil.getSession().save(this);
}

private void setMessages(List /* ChatMessage */ messages) {
this.messages = new SavedMessage[messages.size()];
int i = 0;
Iterator it = messages.iterator();
while (it.hasNext()) {
ChatMessage m = (ChatMessage) it.next();
this.messages[i] = new SavedMessage(m);
i++;
}
}

public List /* SavedMessage */ getMessages() {
if (messages == null)
messages = new SavedMessage[0];
return Arrays.asList(messages);
}