public StAXSource(XMLStreamReader xmlStreamReader) 
{
        if (xmlStreamReader == null) {
            throw new IllegalArgumentException("XMLStreamReader cannot be null.");
        }
        final int event = xmlStreamReader.getEventType();
        if (event != XMLStreamConstants.START_DOCUMENT && 
            event != XMLStreamConstants.START_ELEMENT) {
            throw new IllegalStateException("The state of the XMLStreamReader must be START_DOCUMENT or START_ELEMENT");
        }
        this.xmlStreamReader = xmlStreamReader;
        this.xmlEventReader = null;
        this.systemId = xmlStreamReader.getLocation().getSystemId();
}

 public StAXSource(XMLEventReader xmlEventReader) throws XMLStreamException 
{
        if (xmlEventReader == null) {
            throw new IllegalArgumentException("XMLEventReader cannot be null.");
        }
        final XMLEvent event = xmlEventReader.peek();
        if (!event.isStartDocument() && 
            !event.isStartElement()) {
            throw new IllegalStateException("The state of the XMLEventReader must be START_DOCUMENT or START_ELEMENT");
        }
        this.xmlStreamReader = null;
        this.xmlEventReader = xmlEventReader;
        this.systemId = event.getLocation().getSystemId();
}

 public String getSystemId() 
{
        return systemId;
}

 public XMLEventReader getXMLEventReader() 
{
        return xmlEventReader;
}

 public XMLStreamReader getXMLStreamReader() 
{
        return xmlStreamReader;
}

 public  void setSystemId(String systemId) 
{
        throw new UnsupportedOperationException("Setting systemId is not supported.");
}