I create a pipeline that first collects the data in a class called
DataManager. The XML and XSL documents are stored in a bean. After that,
I call the transform function in another class (static method, see
below). It seems to me that it's just a standard transformation. No
exception is thrown. If I assume that the Transformer does its job, what
else could it be then my wild guess?

    public static void transform(ReportOutput r) throws
        XSLTTransformException {

        Document XMLDoc = r.getXMLDoc();
        Document XSLDoc = r.getXSLTDoc();

        if(XSLDoc == null ) {
            r.setOutput(xmlToString(XMLDoc));
            return;
        }

        try {
            // Create a TransformerFactory
            TransformerFactory tFactory =                    
TransformerFactory.newInstance();

            // Use the DOM XML Document to define a DOMSource object.
            DOMSource xmlDomSource = new DOMSource(XMLDoc);

            // Use the DOM XSL Document to define a DOMSource object.
            DOMSource xslDomSource = new DOMSource(XSLDoc);

            //Create a StringWriter to collect the output
            StringWriter sw = new StringWriter();

            // Create a StreamResult from the StringWriter
            StreamResult SResult = new StreamResult(sw);

            // Process the stylesheet DOMSource and generate a

            //Transformer.
            Transformer transformer =
                     tFactory.newTransformer(xslDomSource);

            // Perform the transformation, placing the output in the
            //StreamResult.
            transformer.transform(xmlDomSource, SResult);

            r.setOutput(sw.getBuffer().toString());

        } catch (TransformerException e) {
            ModelUtils.log(e);
            throw new XSLTTransformException();
        }
    }