SOAPMessage returned from SOAPMessageContext doesn't support DOM

The SOAPMessage returned from SOAPConnection.call() fully supports access via DOM API.
However, the SOAPMessage returned from SOAPMessageContext (when writing a SOAPHandler) does not.
Namely, SOAPBody.getElementsByTagName() results in a JBoss NotImplementedException.
Also, using SOAPElement.getChildElements() on the SOAPBody, and then navigating down to the <arg0> element, I cannot use Node.getTextContent() -> again get a NotImplementedException.
Only workaround is to navigate all the way down to the text node contained by <arg0>, and then call Node.getNodeValue() on that.

How did this pass the Sun verification tests?