class XfaFile implements OutputStreamResource {

    /**
     * The X4J Document object (XML).
     */
    protected Document xfaDocument;

    /**
     * Constructs an XFA file from an OutputStreamResource. This resource can be an XML file or a node in a RUPS
     * application.
     *
     * @param resource the XFA resource
     * @throws IOException       thrown when an I/O operation goes wrong
     * @throws DocumentException thrown when something goes wrong with a Document
     */
    public XfaFile(OutputStreamResource resource) throws IOException, DocumentException {
        // Is there a way to avoid loading everything in memory?
        // Can we somehow get the XML from the PDF as an InputSource, Reader or InputStream?
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        resource.writeTo(baos);
        ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());
        SAXReader reader = new SAXReader();
        xfaDocument = reader.read(bais);
    }

    /**
     * Getter for the XFA Document object.
     *
     * @return a Document object (X4J)
     */
    public Document getXfaDocument() {
        return xfaDocument;
    }

    /**
     * Writes a formatted XML file to the OutputStream.
     *
     * @see com.lowagie.rups.io.OutputStreamResource#writeTo(java.io.OutputStream)
     */
    public void writeTo(OutputStream os) throws IOException {<FILL_FUNCTION_BODY>}
}

        if (xfaDocument == null) {
            return;
        }
        OutputFormat format = new OutputFormat("   ", true);
        XMLWriter writer = new XMLWriter(os, format);
        writer.write(xfaDocument);
    
<no_super_class>