final ByteArrayOutputStream out = new ByteArrayOutputStream();
    InputStream in = null;
    InputStream xsl = null;
    try {
        in = inputFileStream;
        xsl = url.openStream();
        final TransformerFactory tFactory = TransformerFactory
                .newInstance();
        final Transformer transformer = tFactory
                .newTransformer(new StreamSource(xsl));
        transformer.transform(new StreamSource(in), new StreamResult(out));
    } catch (Throwable t) {
        Activator.logErrorMessage(NLS.bind(
                Messages.Import_XSLT_TRANSFORMATION_FAILED, t.toString()));
    } finally {
        IOUtils.closeQuietly(xsl);
        IOUtils.closeQuietly(in);
        IOUtils.closeQuietly(out);
    }

final Transformer transformer = templates.newTransformer();
transformer.setParameter("containerFullPath", containerFullPath);
transformer.transform(new StreamSource(in), new StreamResult(out));

<xsl:param name="containerFullPath"/> <!-- at the root of the xslt -->
...
    <redirect:write  file="{$containerFullPath}/{$modelName}-{@name}.bpmn">
...