How to configure fonts from Java code in Apache FOP?

The link says that it is not "easily" possible to configure fonts from java code. How do I achieve this? I'm having problems rendering certain HTMLs from international languages like French and Japanese.

WARNING: Font "Symbol,normal,700" not found. Substituting with "Symbol,normal,400".
May 08, 2015 4:45:39 PM org.apache.fop.events.LoggingEventListener processEvent
WARNING: Font "ZapfDingbats,normal,700" not found. Substituting with "ZapfDingbats,normal,400". 

The PDF generated is damaged as a result.

update:

My Html contains French words like "Modifié Créée le Propriétaire"

File file = new File("C:\\Users\\me\\Desktop\\Test.html");


fopFactory = FopFactory.newInstance();
foUserAgent = fopFactory.newFOUserAgent();


String fileName = file.getAbsolutePath().substring(file.getAbsolutePath().lastIndexOf("\\")+1,file.getAbsolutePath().lastIndexOf("."));
        String workspacePath = file.getAbsolutePath().substring(0,file.getAbsolutePath().lastIndexOf("\\"));
        File xsltfile = new File("xhtml2fo.xsl");
        StreamSource source = null;
        source = new StreamSource(file);
        StreamSource transformSource = new StreamSource(xsltfile);
        ByteArrayOutputStream outStream = new ByteArrayOutputStream();


        Transformer xslfoTransformer = null;
        TransformerFactory fac = TransformerFactory.newInstance();
        xslfoTransformer = fac.newTransformer(transformSource);
        xslfoTransformer.setErrorListener(this);

        Fop fop;
        fop = fopFactory.newFop(MimeConstants.MIME_PDF, foUserAgent, outStream);
        // Resulting SAX events (the generated FO)
        Result res = new SAXResult(fop.getDefaultHandler());
        xslfoTransformer.transform(source, res);

        output = new File(workspacePath + File.separator + fileName + ".pdf");
        OutputStream out = new java.io.FileOutputStream(output);
        out = new java.io.BufferedOutputStream(out);
        FileOutputStream str = new FileOutputStream(output);
        str.write(outStream.toByteArray());
        str.close();

I'm using an XSLT provided by Antennahouse to convert HTML tags to FO tags.