HttpProxy Post example

I need an example of the use of POST in HttpProxy.

I want to send an object from the client to the server.

I want to complete this code:

Code:

RequestBuilder builder = new RequestBuilder(RequestBuilder.POST,
                                        path);
HttpProxy<PagingLoadConfig> proxy = new HttpProxy<PagingLoadConfig>(
                                        builder);
proxy.setWriter(new PagingLoadUrlEncoder());


///////

public class PagingLoadUrlEncoder implements
                DataWriter<PagingLoadConfig, String> {
      
       public String write(PagingLoadConfig config) {
               MyObjectClassToSend obj;
               String str;

               ????????????????

               return str;

      }
}

Ideas?

Thanks in Advance