Issue #0: Fixed wildcard mapping on Posts migration

src/Plugin/migrate/source/Posts.php

@@ -133,7 +133,7 @@ class Posts extends SqlBase {
     $query->join(
       $this->getTableName('postmeta'),
         'pm',
-        'p.id = pm.post_id and pm.meta_key = :attached_file',
+        'p.id = pm.post_id and pm.meta_key = :meta_key',
         [':meta_key' => $meta_key],
       );
     $query->condition('p.id', $post_id);