public class CustomSerializeSession implements SessionCustomizer  {
  
    public void customize(Session session) throws Exception {
      for (Iterator<?> dI = session.getProject().getAliasDescriptors()
          .values().iterator(); dI.hasNext();) {
        ClassDescriptor descriptor = (ClassDescriptor) dI.next();
        for (Iterator<?> mI = descriptor.getMappings().iterator(); mI
            .hasNext();) {
          DatabaseMapping mapping = (DatabaseMapping) mI.next();
          // only for relationships set to lazy
          if (mapping.isForeignReferenceMapping()
              && mapping.isCollectionMapping()
              && mapping.isLazy()) {
            CollectionMapping colMapping = (CollectionMapping) mapping;
            if (colMapping.getContainerPolicy().getContainerClass() == ClassConstants.IndirectList_Class) {
              
              ListContainerPolicy policy = new ListContainerPolicy(
                  CustomSerializeIndirectList.class);
              colMapping.setContainerPolicy(policy);
            } 
          }
        }
      }
    }
}

public class CustomSerializeIndirectList extends IndirectList {

	public CustomSerializeIndirectList() {
		super();
	}

	public CustomSerializeIndirectList(int size) {
		super(size);
	}

	public Object writeReplace() throws ObjectStreamException {
		if (!isInstantiated()) {
			return null;
		}
		return this;
	}
}