public void convert(InputStream xml, InputStream xslt, OutputStream outputStream, String mimeConstants) throws Exception {
try {
ByteArrayOutputStream out = new ByteArrayOutputStream();
FopFactory fopFactory = FopFactory.newInstance();
FOUserAgent foUserAgent = fopFactory.newFOUserAgent();
Fop fop = fopFactory.newFop(mimeConstants, foUserAgent, out);
TransformerFactory factory = TransformerFactory.newInstance();
Transformer transformer = factory.newTransformer(new StreamSource(xslt));
transformer.setParameter("versionParam", "2.0");
Source src = new StreamSource(xml);
Result res = new SAXResult(fop.getDefaultHandler());