Not working with apachesolr-6.x-2.x-dev

Even though view integration works properly with apachesolr-6.x-1.0-rc2.tar.gz, it makes the following fatal error with apachesolr-6.x-2.x-dev:

Fatal error: Class apachesolr_views_query contains 2 abstract methods and must therefore be declared abstract or implement the remaining methods (Drupal_Solr_Query_Interface::get_keys, Drupal_Solr_Query_Interface::set_keys) in [path-to-drupal]sites/all/modules/contrib/apachesolr_views/apachesolr_views_query.inc on line 698