@Override
    public SOAPEnvelope unmarshall(InputStream input) throws Exception {
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        factory.setNamespaceAware(true);
        factory.setValidating(false);
        DocumentBuilder builder = factory.newDocumentBuilder();
        Document doc = builder.parse(input);
        SOAPElement soapElement = SOAPFactory.newInstance().createElement(doc.getDocumentElement());
        SOAPEnvelope envelope = (SOAPEnvelope) soapElement;
        return envelope;
    }
@see io.apiman.gateway.engine.io.IPayloadIO#unmarshall(java.io.InputStream)
gateway/engine/core/src/main/java/io/apiman/gateway/engine/io/SoapPayloadIO.java