hibernate "IllegalArgumentException occurred calling getter"

Here's my class hierarchy (lombok generated constructors/getters/setters ommitted for brevity):

public class A
{
    ... other variables ...

    @OneToMany(fetch=FetchType.LAZY, cascade = {CascadeType.ALL})
    private Set<B> bSet = new HashSet<B>();
}

public class B
{
    ... other variables ...

    @CollectionOfElements
    @IndexColumn(name="index")
    private List<C> cList = new ArrayList<C>();
}

public class C
{
    ... other variables ...

    @Embedded
    private D[] dArray;
}

@Embeddable
public class D
{
    ... other variables ...

    private float f1;

    private float f2;
}

The problem is that when I save a new A instance that has stuff in the bSet, I get an IllegalArgumentException. Here's the relevant parts of the stack trace:

 org.hibernate.PropertyAccessException: IllegalArgumentException occurred calling getter of path.to.D.f1
    at path.to.dao.commitTransaction(PersistableDAO.java:32)
    at path.to.daoCaller(daoCaller.java:79)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    ... omitted for brevity ...
Caused by: org.hibernate.PropertyAccessException: IllegalArgumentException occurred calling getter of path.to.D.f1
    at org.hibernate.property.BasicPropertyAccessor$BasicGetter.get(BasicPropertyAccessor.java:195)
    at org.hibernate.tuple.component.AbstractComponentTuplizer.getPropertyValue(AbstractComponentTuplizer.java:87)
    at org.hibernate.tuple.component.AbstractComponentTuplizer.getPropertyValues(AbstractComponentTuplizer.java:93)
    at org.hibernate.tuple.component.PojoComponentTuplizer.getPropertyValues(PojoComponentTuplizer.java:109)
    at org.hibernate.type.ComponentType.getPropertyValues(ComponentType.java:376)
    at org.hibernate.type.ComponentType.deepCopy(ComponentType.java:419)
    at org.hibernate.type.ComponentType.deepCopy(ComponentType.java:421)
    at org.hibernate.collection.PersistentList.getSnapshot(PersistentList.java:61)
    at org.hibernate.engine.CollectionEntry.<init>(CollectionEntry.java:91)
    at org.hibernate.engine.StatefulPersistenceContext.addCollection(StatefulPersistenceContext.java:807)
    at org.hibernate.engine.StatefulPersistenceContext.addNewCollection(StatefulPersistenceContext.java:774)
    at org.hibernate.event.def.WrapVisitor.processArrayOrNewCollection(WrapVisitor.java:108)
    at org.hibernate.event.def.WrapVisitor.processCollection(WrapVisitor.java:74)
    at org.hibernate.event.def.AbstractVisitor.processValue(AbstractVisitor.java:124)
    at org.hibernate.event.def.WrapVisitor.processValue(WrapVisitor.java:121)
    at org.hibernate.event.def.AbstractVisitor.processEntityPropertyValues(AbstractVisitor.java:78)
    at org.hibernate.event.def.AbstractSaveEventListener.visitCollectionsBeforeSave(AbstractSaveEventListener.java:394)
    at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:296)
    at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:204)
    at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:130)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:210)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:195)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:117)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:93)
    at org.hibernate.impl.SessionImpl.fireSaveOrUpdate(SessionImpl.java:535)
    at org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:527)
    at org.hibernate.engine.CascadingAction$5.cascade(CascadingAction.java:241)
    at org.hibernate.engine.Cascade.cascadeToOne(Cascade.java:292)
    at org.hibernate.engine.Cascade.cascadeAssociation(Cascade.java:240)
    at org.hibernate.engine.Cascade.cascadeProperty(Cascade.java:193)
    at org.hibernate.engine.Cascade.cascadeCollectionElements(Cascade.java:320)
    at org.hibernate.engine.Cascade.cascadeCollection(Cascade.java:266)
    at org.hibernate.engine.Cascade.cascadeAssociation(Cascade.java:243)
    at org.hibernate.engine.Cascade.cascadeProperty(Cascade.java:193)
    at org.hibernate.engine.Cascade.cascade(Cascade.java:154)
    at org.hibernate.event.def.AbstractSaveEventListener.cascadeAfterSave(AbstractSaveEventListener.java:479)
    at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:357)
    at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:204)
    at org.hibernate.event.def.AbstractSaveEventLi开发者_如何学Pythonstener.saveWithGeneratedId(AbstractSaveEventListener.java:130)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:210)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:195)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:117)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:93)
    at org.hibernate.impl.SessionImpl.fireSaveOrUpdate(SessionImpl.java:535)
    at org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:527)
    at org.hibernate.engine.CascadingAction$5.cascade(CascadingAction.java:241)
    at org.hibernate.engine.Cascade.cascadeToOne(Cascade.java:292)
    at org.hibernate.engine.Cascade.cascadeAssociation(Cascade.java:240)
    at org.hibernate.engine.Cascade.cascadeProperty(Cascade.java:193)
    at org.hibernate.engine.Cascade.cascadeCollectionElements(Cascade.java:320)
    at org.hibernate.engine.Cascade.cascadeCollection(Cascade.java:266)
    at org.hibernate.engine.Cascade.cascadeAssociation(Cascade.java:243)
    at org.hibernate.engine.Cascade.cascadeProperty(Cascade.java:193)
    at org.hibernate.engine.Cascade.cascade(Cascade.java:154)
    at org.hibernate.event.def.AbstractFlushingEventListener.cascadeOnFlush(AbstractFlushingEventListener.java:154)
    at org.hibernate.event.def.AbstractFlushingEventListener.prepareEntityFlushes(AbstractFlushingEventListener.java:145)
    at org.hibernate.event.def.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:88)
    at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:49)
    at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1028)
    at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:366)
    at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:137)
    at path.to.dao.commitTransaction(PersistableDAO.java:28)
    ... 52 more
Caused by: java.lang.IllegalArgumentException: object is not an instance of declaring class
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.hibernate.property.BasicPropertyAccessor$BasicGetter.get(BasicPropertyAccessor.java:169)
    ... 113 more

Can anyone tell me what's going on?

Thanks!

AFAIK, you can't persist an array of Embeddable. In other words, the following is not supported:

public class C {
    ... other variables ...

    @Embedded
    private D[] dArray;
}

From the JPA 1.0 specification:

2.1.5 Embeddable Classes

An entity may use other fine-grained classes to represent entity state. Instances of these classes, unlike entity instances themselves, do not have persistent identity. Instead, they exist only as embedded objects of the entity to which they belong. Such embedded objects belong strictly to their owning entity, and are not sharable across persistent entities. Attempting to share an embedded object across entities has undefined semantics. Because these objects have no persistent identity, they are typically mapped together with the entity instance to which they belong.

Embeddable classes must adhere to the requirements specified in Section 2.1 for entities with the exception that embeddable classes are not annotated as Entity. Embeddable classes must be annotated as Embeddable or denoted in the XML descriptor as such. The access type for an embedded object is determined by the access type of the entity in which it is embedded. Support for only one level of embedding is required by this specification.

Additional requirements on embeddable classes are described in section 9.1.34.

JPA 2.0 added support for collections of embedded objects:

2.6 Collections of Embeddable Classes and Basic Types

A persistent field or property of an entity or embeddable class may correspond to a collection of a basic type or embeddable class (“element collection”). Such a collection, when specified as such by the ElementCollection annotation, is mapped by means of a collection table, as defined in Section 11.1.8. If the ElementCollection annotation (or XML equivalent) is not specified for the collection-valued field or property, the rules of Section 2.8 apply.

An embeddable class (including an embeddable class within another embeddable class) that is contained within an element collection must not contain an element collection, nor may it contain a relationship to an entity other than a many-to-one or one-to-one relationship. The embeddable class must be on the owning side of such a relationship and the relationship must be mapped by a foreign key mapping. (See Section 2.9.)

But I still don't think you can map an array of Embeddable.