SOAPAddressingPropertiesImpl#writeHeaders has these two lines:

SOAPFactoryImpl factory = (SOAPFactoryImpl)SOAPFactory.newInstance();
SOAPHeader soapHeader = message.getSOAPHeader();

soapHeader is then used without catching a NullPointerException ...

The cast conflicts with the currently set System property, resulting in a ClassCastException. That happens because I was just using the WS-Addressing part of jbossws. By the way, is there any other implementation of JSR261 available?