code: public static void writeGen(JavaFileObject fileObject, JsonModelModel model) throws IOException {
  		Map<String, Object> map = convModelToMap(model);
  
  		Writer writer = fileObject.openWriter();
  		PrintWriter printWriter = new PrintWriter(writer);
  		String generated =
  				(String) TemplateRuntime.eval(getTemplateString("JsonModelGen.java.mvel"), map);
  		try {
  			printWriter.write(generated);
  			printWriter.flush();
  			printWriter.close();
  		} catch (Exception e) {
  			throw new RuntimeException("error raised in process " + model.getTarget(), e);
  		}
  	}
docs: Generates source code into the given file object from the given data model, utilizing the templating engine.
  @param fileObject Target file object
  @param model Data model for source code generation
  @throws IOException
  @author vvakame