In JAXB Marshalling, how to determine which child threw a JAXB Marshalling exception?

I get this exception when marhsalling my JAXBElement, which has multiple children. How to figure out how to determine which child has raised this exception?

java.lang.NullPointerException
    at com.sun.xml.bind.v2.runtime.property.AttributeProperty.getIdValue(AttributeProperty.java:128)
    at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.getId(ClassBeanInfoImpl.java:320)
    at com.sun.xml.bind.v2.runtime.reflect.TransducedAccessor$IDREFTransducedAccessorImpl.print(TransducedAccessor.java:290)
    at com.sun.xml.bind.v2.runtime.reflect.TransducedAccessor$IDREFTransducedAccessorImpl.print(TransducedAccessor.java:271)
    at com.sun.xml.bind.v2.runtime.property.AttributeProperty.serializeAttributes(AttributeProperty.java:101)
    at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.serializeAttributes(ClassBeanInfoImpl.java:375)
    at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsXsiType(XMLSerializer.java:689)
    at com.sun.xml.bind.v2.runtime.property.SingleElementNodeProperty.serializeBody(SingleElementNodeProperty.java:158)
    at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.serializeBody(ClassBeanInfoImpl.java:358)
    at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsXsiType(XMLSerializer.java:696)
    at com.sun.xml.bind.v2.runtime.property.SingleElementNodeProperty.serializeBody(SingleElementNodeProperty.java:158)
    at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.serializeBody(ClassBeanInfoImpl.java:358)
    at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsXsiType(XMLSerializer.java:696)
    at com.sun.xml.bind.v2.runtime.property.ArrayElementNodeProperty.serializeItem(ArrayElementNodeProperty.java:69)
    at com.sun.xml.bind.v2.runtime.property.ArrayElementProperty.serializeListBody(ArrayElementProperty.java:172)
    at com.sun.xml.bind.v2.runtime.property.ArrayERProperty.serializeBody(ArrayERProperty.java:159)
    at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.serializeBody(ClassBeanInfoImpl.java:358)
    at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsXsiType(XMLSerializer.java:696)
    at com.sun.xml.bind.v2.runtime.property.SingleElementNodeProperty.serializeBody(SingleElementNodeProperty.java:158)
    at com.sun.xml.bind.v2.runtime.ElementBeanInfoImpl$1.serializeBody(ElementBeanInfoImpl.java:161)
    at com.sun.xml.bind.v2.runtime.ElementBeanInfoImpl$1.serializeBody(ElementBeanInfoImpl.java:131)
    at com.sun.xml.bind.v2.runtime.ElementBeanInfoImpl.serializeBody(ElementBeanInfoImpl.java:333)
    at com.sun.xml.bind.v2.runtime.ElementBeanInfoImpl.serializeRoot(ElementBeanInfoImpl.java:340)
    at com.sun.xml.bind.v2.runtime.ElementBeanInfoImpl.serializeRoot(ElementBeanInfoImpl.java:76)
    at com.sun.xml.bind.v2.runtime.property.SingleReferenceNodeProperty.serializeBody(SingleReferenceNodeProperty.java:115)
    at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.serializeBody(ClassBeanInfoImpl.java:358)
    at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsXsiType(XMLSerializer.java:696)
    at com.sun.xml.bind.v2.runtime.property.SingleElementNodeProperty.serializeBody(SingleElementNodeProperty.java:158)
    at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.serializeBody(ClassBeanInfoImpl.java:358)
    at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsXsiType(XMLSerializer.java:696)
    at com.sun.xml.bind.v2.runtime.property.SingleElementNodeProperty.serializeBody(SingleElementNodeProperty.java:158)
    at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.serializeBody(ClassBeanInfoImpl.java:358)
    at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsXsiType(XMLSerializer.java:696)
    at com.sun.xml.bind.v2.runtime.property.ArrayElementNodeProperty.serializeItem(ArrayElementNodeProperty.java:69)
    at com.sun.xml.bind.v2.runtime.property.ArrayElementProperty.serializeListBody(ArrayElementProperty.java:172)
    at com.sun.xml.bind.v2.runtime.property.ArrayERProperty.serializeBody(ArrayERProperty.java:159)
    at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.serializeBody(ClassBeanInfoImpl.java:358)
    at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsXsiType(XMLSerializer.java:696)
    at com.sun.xml.bind.v2.runtime.ElementBeanInfoImpl$1.serializeBody(ElementBeanInfoImpl.java:156)
    at com.sun.xml.bind.v2.runtime.ElementBeanInfoImpl$1.serializeBody(ElementBeanInfoImpl.java:131)
    at com.sun.xml.bind.v2.runtime.ElementBeanInfoImpl.serializeBody(ElementBeanInfoImpl.java:333)
    at com.sun.xml.bind.v2.runtime.ElementBeanInfoImpl.serializeRoot(ElementBeanInfoImpl.java:340)
    at com.sun.xml.bind.v2.runtime.ElementBeanInfoImpl.serializeRoot(ElementBeanInfoImpl.java:76)
    at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsRoot(XMLSerializer.java:494)
    at com.sun.xml.bind.v2.runtime.MarshallerImpl.write(MarshallerImpl.java:323)
    at com.sun.xml.bind.v2.runtime.MarshallerImpl.marshal(MarshallerImpl.java:251)
    at javax.xml.bind.helpers.AbstractMarshallerImpl.marshal(AbstractMarshallerImpl.java:75)
    at com.tdsecurities.fxdev.doddfranktdmladapter.SwapTDMLGeneratorJunitTest.testHello(SwapTDMLGeneratorJunitTest.java:113)

This is the code I use to sort Jaxbelment:

JAXBElementdmlJAXBElement = SwapDMLGenerator.generateDML (event, leg1ordMm, leg2ordMm, leg1OrdCs, leg2OrdCs);

JAXBContext jaxbContext_m = JAXBContext.newInstance(DmlWrapper.class);
Marshaller marshaller = jaxbContext_m.createMarshaller();
//marshaller.setProperty(Marshaller.JAXB_SCHEMA_LOCATION, "");
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);        
String  outFileName= String.format("dml-%d-ordm_deallnum-%s.xml",System.currentTimeMillis(), .getDealNumber());
File fout= new File(destDir, outFileName);
FileOutputStream fos= new FileOutputStream(fout);
marshaller.marshal(dmlJAXBElement, fos);
fos.close();