/**
  * We need to disable Translatable before retreiving the DataObjects or 
  * Pages for the sitemap, because otherwise only pages in the default 
  * language are found.
  * 
  * Next we need to add the alternatives for each Translatable Object 
  * included in the sitemap: basically these are the Translations plus 
  * the current object itself
  * 
  * @return Array
  */
 public function sitemap()
 {
     Translatable::disable_locale_filter();
     $sitemap = parent::sitemap();
     Translatable::enable_locale_filter();
     $updatedItems = new ArrayList();
     foreach ($sitemap as $items) {
         foreach ($items as $item) {
             if ($item->hasExtension('Translatable')) {
                 $translations = $item->getTranslations();
                 if ($translations) {
                     $alternatives = new ArrayList();
                     foreach ($translations as $translation) {
                         $translation->GoogleLocale = $this->getGoogleLocale($translation->Locale);
                         $alternatives->push($translation);
                     }
                     $item->GoogleLocale = $this->getGoogleLocale($item->Locale);
                     $alternatives->push($item);
                     $item->Alternatives = $alternatives;
                 }
                 $updatedItems->push($item);
             }
         }
     }
     if (!empty($updatedItems)) {
         return array('Items' => $updatedItems);
     } else {
         return $sitemap;
     }
 }
 /**
  * Specific controller action for displaying a particular list of links
  * for a class
  *
  * @return mixed
  */
 public function sitemap()
 {
     if ($this->request->param('ID') == 'SiteTree') {
         //Disable the locale filter
         Translatable::disable_locale_filter();
         $items = parent::sitemap();
         //Re-enable the locale filter
         Translatable::enable_locale_filter();
         return $items;
     } else {
         return parent::sitemap();
     }
 }
<?php

SiteTree::add_extension("LocaleDomainSiteTreeExtension");
if (class_exists("GoogleSitemapController")) {
    GoogleSitemapController::add_extension("LocaleDomainsGoogleSitemapControllerExtension");
}
 public function init()
 {
     parent::init();
     // Reset any session locale to use the default locale as the standard 'base' locale
     Fluent::set_persist_locale(Fluent::default_locale(true));
 }