I have been provided with an xsd that I compiled to Java classes using

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Asked: May 31, 20262026-05-31T01:40:39+00:00 2026-05-31T01:40:39+00:00

I have been provided with an xsd that I compiled to Java classes using

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I have been provided with an xsd that I compiled to Java classes using JAXB.

The generated classes create an abstract class called “Event” and several classes that extend it.
e.g. “DerivedEvent”
I am using the following to marshal it to XML.

ObjectFactory objectFactory = new ObjectFactory();
DerivedEvent derivedEvent = objectFactory.createDerivedEvent();

JAXBContext context = JAXBContextImpl.newInstance("com.my.root.namespace");
Marshaller marshaller = context.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
marshaller.setProperty(Marshaller.JAXB_ENCODING, "UTF-8");
marshaller.setProperty(Marshaller.JAXB_FRAGMENT, Boolean.TRUE);

Class partialClass = Event.class;
QName partNamespace = new QName(Event.class.getSimpleName());
Object element = new JAXBElement(partNamespace, partialClass, derivedEvent);
// Create a stringWriter to hold the XML
StringWriter stringWriter = new StringWriter();
marshaller.marshal(element, stringWriter);
String xml = stringWriter.toString();

This then outputs the wrong root element. i.e.

<Event xsi:type="DerivedEvent" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <DerivedStartPeriod xsi:nil="true"/>
    <DerivedEndPeriod xsi:nil="true"/>
</Event>

instead of

<DerivedEvent>
    <DerivedStartPeriod xsi:nil="true" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"/>
    <DerivedEndPeriod xsi:nil="true" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"/>
</DerivedEvent>

If I set the partialClass and partNamespace to DerivedEvent it outputs the correct information.
However, I can’t really do that as this marshalling is in a flow where the event could be one of 50 different derived events.

I can’t really change the xsd to have substitution groups as mentioned here http://blog.bdoughan.com/2010/11/jaxb-and-inheritance-using-substitution.html as this change is likely to be lost when I am provided with a new version of the xsd.

I need to use the partial class and namespace as the Events are not root elements.
Can I add the events to be XmlRootElements with bindings somehow?
Or is there another way to address this?