Probleminha com FOP

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.avalon.framework.logger.ConsoleLogger;
import org.apache.avalon.framework.logger.Logger;
import org.apache.fop.apps.Driver;
import org.apache.fop.messaging.MessageHandler;
import org.xml.sax.InputSource;

public class FopServlet extends HttpServlet {
    Logger log = null;

    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException {
		try {
	
	        if (log == null) {
	            log = new ConsoleLogger(ConsoleLogger.LEVEL_WARN);
	            MessageHandler.setScreenLogger(log);
	        }

            File fofile = new File("contrato.fo");
            FileInputStream file = new FileInputStream(fofile);
            renderFO(new InputSource(file), response);
        } catch (ServletException ex) {
            throw ex;
        }
        catch (Exception ex) {
            throw new ServletException(ex);
        }
    }

    /**
     * Renders an FO inputsource into a PDF file which is written
     * directly to the response object's OutputStream
     */
    public void renderFO(InputSource foFile,
                         HttpServletResponse response) throws ServletException {
        try {
            ByteArrayOutputStream out = new ByteArrayOutputStream();

            response.setContentType("application/pdf");

            Driver driver = new Driver(foFile, out);
            driver.setLogger(log);
            driver.setRenderer(Driver.RENDER_PDF);
            driver.run();

            byte[] content = out.toByteArray();
            response.setContentLength(content.length);
            response.getOutputStream().write(content);
            response.getOutputStream().flush();
        } catch (Exception ex) {
            throw new ServletException(ex);
        }
    }
}

import java.awt.Dimension;
import java.awt.Toolkit;
import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;
import java.net.URL;

import javax.swing.WindowConstants;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import org.apache.avalon.framework.logger.ConsoleLogger;
import org.apache.fop.apps.Driver;
import org.apache.fop.apps.FOPException;
import org.apache.fop.render.awt.AWTRenderer;
import org.apache.fop.viewer.PreviewDialog;
import org.apache.fop.viewer.SecureResourceBundle;
import org.apache.fop.viewer.Translator;
import org.apache.fop.viewer.UserMessage;
import org.xml.sax.InputSource;
import org.xml.sax.helpers.ParserAdapter;

public final class VisualizadorFOP {
	public static final String TRANSLATION_PATH = "/org/apache/fop/viewer/resources/";
	protected PreviewDialog createPreviewDialog(AWTRenderer renderer, Translator res){
		PreviewDialog frame = new PreviewDialog(renderer, res);
		frame.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
		frame.validate();
		frame.setTitle("Visualizar impressão");

		/** Descobre o tamanho da janela */
		Dimension screen = Toolkit.getDefaultToolkit().getScreenSize(); 
		frame.setSize(screen);

		frame.setVisible(true);
		return frame;
	}

	public final SecureResourceBundle getResourceBundle(String path) throws IOException{
		URL url = getClass().getResource(path);
		if(url == null){
			path = path.substring(0, path.lastIndexOf(".")) + ".en"; 
			url = getClass().getResource(path);
		}
		
		return new SecureResourceBundle(url.openStream());
	}

	public final void visualizaXSLFO(String arquivoXSLFO) throws IOException, FOPException {
		String linguagem = System.getProperty("user.language");
		Translator translator = getResourceBundle(TRANSLATION_PATH + "resources." + linguagem);
		translator.setMissingEmphasized(false);
		UserMessage.setTranslator(getResourceBundle(TRANSLATION_PATH + "messages." + linguagem));
		
		AWTRenderer renderer = new AWTRenderer(translator);
		PreviewDialog frame = createPreviewDialog(renderer, translator);
		renderer.setProgressListener(frame);
		renderer.setComponent(frame);
		
		try{
			SAXParserFactory factory = SAXParserFactory.newInstance();
			SAXParser parser = factory.newSAXParser();
			Reader in = new FileReader(arquivoXSLFO);
			
			Driver driver = new Driver();
			driver.setLogger(new ConsoleLogger(ConsoleLogger.LEVEL_INFO));
			driver.setRenderer(renderer);
			driver.render(new ParserAdapter(parser.getParser()), new InputSource(in));
			in.close();
			frame.showPage();
		}
		catch(Exception e){
			frame.reportException(e);
			
			if(e instanceof FOPException){
				throw (FOPException) e;
			}
			
			throw new FOPException(e);
		}

	}
}