public void exportToXMI(String filename) {
   XMIWriterFactory factory = XMIWriterFactory.getDefault();
   XMIWriter writer = factory.createXMIWriter();
   writer.getConfiguration().setEncoding("UTF-8");
   try {
     writer.write(new FileOutputStream(filename), spagobiPackage, "1.2"); // $NON-NLS-1$
   } catch (Throwable t) {
     throw new RuntimeException("Impossible to export cwm model [" + name + "] to xmi", t);
   }
 }