Issue #2249723 by andrei.dincu: Replace self with static in XmlSitemapGenerator Service, replace url_alias.language with url_alias.langcode
Issue #2249723 by andrei.dincu: Replace variable_get() and variable_set() with Drupal 8 get() and set() in xmlsitemap_regenerate_batch_finished
Issue #2249723 by andrei.dincu: Create XmlSitemapController class and add method to output sitemap in xsl format