private Product createProduct(String id) {
    Product product = new Product();
    product.title = "Red wool sweater";
    product.content =
        new Content(
            "text",
            "Comfortable and soft, this sweater will keep you warm on those "
            + "cold winter nights. Red and blue stripes.");
    product.appControl = new AppControl();
    product.appControl.addRequiredDestination("ProductAds");

    product.externalId = id;
    product.lang = "it";
    product.country = "it";
    product.condition = "nuovo";
    product.price = new Price("EUR", new BigDecimal("12.99"));
    product.googleProductCategory = "Sporting Goods > Exercise & Fitness > Cardio Machines > Exercise Bikes";

    // add a link
    Link link = new Link();
    link.rel = "alternate";
    link.href = homepage + "item1-info-page.html";
    link.type = "text/html";
    product.links.add(link);

    //shipping
    List<com.google.api.client.sample.structuredcontent.model.Shipping> shipping = new ArrayList<com.google.api.client.sample.structuredcontent.model.Shipping>();
    com.google.api.client.sample.structuredcontent.model.Shipping s = new com.google.api.client.sample.structuredcontent.model.Shipping();

    s.shippingCountry="IT";
    Price p = new Price();
    p.unit = "EUR";
    p.value = new BigDecimal("0");
    s.shippingPrice= p;
    //s.shippingRegion=""
    s.shippingService = "Speedy Shipping - Ground";
    shipping.add(s);
    product.shippingRules = shipping;

    //tax
    //Useless in italy
    // set image links
    List<String> imageLinks = new ArrayList<String>();
    imageLinks.add("http://www.example.com/image1.jpg");
    imageLinks.add("http://www.example.com/image2.jpg");
    product.imageLinks = imageLinks;

    return product;
  }

<?xml version="1.0"?>
<entry xmlns="http://www.w3.org/2005/Atom" xmlns:app="http://www.w3.org/2007/app" xmlns:sc="http://schemas.google.com/structuredcontent/2009" xmlns:scp="http://schemas.google.com/structuredcontent/2009/products"><app:control><sc:required_destination dest="ProductAds" />
</app:control>
<content type="text">
Comfortable and soft, this sweater will keep you warm on those cold winter nights. Red and blue stripes.</content>
<link href="http://www.joinstore.it/item1-info-page.html" rel="alternate" type="text/html" />
<sc:adult>false</sc:adult><sc:content_language>it</sc:content_language>
<sc:id>1234567</sc:id>
<sc:image_link>http://www.example.com/image1.jpg</sc:image_link>
<sc:image_link>http://www.example.com/image2.jpg</sc:image_link>
<sc:target_country>it</sc:target_country>
<scp:condition>nuovo</scp:condition>
<scp:featured_product>false</scp:featured_product>
<scp:google_product_category>Sporting Goods > Exercise & Fitness > Cardio Machines > Exercise Bikes</scp:google_product_category>
<scp:price unit="EUR">12.99</scp:price>
<scp:shipping><scp:shipping_country>IT</scp:shipping_country>
<scp:shipping_price unit="EUR">0</scp:shipping_price>
<scp:shipping_service>Speedy Shipping - Ground</scp:shipping_service></scp:shipping>
<title>Red wool sweater</title>
</entry>

// HTTP request
HttpRequest request = requestFactory.buildPostRequest(new GoogleUrl(url), atomContent);
File f = new File(Main.BASE_FOLDER_PATH + "ciao.xml");
FileOutputStream out = new FileOutputStream(f);
request.getContent().writeTo(out);
out.close();
HttpResponse re = null;
re =  request.execute();