Issue #2233887 by benjy: Alias Destination is broken.

core/modules/migrate/lib/Drupal/migrate/Plugin/migrate/destination/UrlAlias.php

@@ -64,7 +64,7 @@ public static function create(ContainerInterface $container, array $configuratio
    */
   public function import(Row $row, array $old_destination_id_values = array()) {
 
-    $path = $this->path->save(
+    $path = $this->aliasStorage->save(
       $row->getDestinationProperty('source'),
       $row->getDestinationProperty('alias'),
       $row->getDestinationProperty('langcode'),