docs: private MultipartBody createMultipartBody() throws Exception  {
          List<Attachment> atts = new LinkedList<Attachment>();
          atts.add(new Attachment("book1", "application/xml", new Book("JAXB", 1L)));
          atts.add(new Attachment("book2", "application/json", new Book("JSON", 2L)));
          
          atts.add(new Attachment("image", "application/octet-stream",
                                  getClass().getResourceAsStream("/java.jpg")));
          
          return new MultipartBody(atts, true);  
  
      }