Add following meta key to Jetpack sync allowlist (#2226)

Author: obenland

.github/changelog/2226-from-description

@@ -0,0 +1,4 @@
+Significance: minor
+Type: added
+
+Sync following meta to enable RSS feed subscriptions for ActivityPub actors in WordPress.com Reader

integration/class-jetpack.php

@@ -8,6 +8,7 @@
 namespace Activitypub\Integration;
 
 use Activitypub\Collection\Followers;
+use Activitypub\Collection\Following;
 use Activitypub\Comment;
 
 /**
@@ -32,14 +33,10 @@ public static function init() {
 	 * @return array The Jetpack sync allow list with ActivityPub meta keys.
 	 */
 	public static function add_sync_meta( $allow_list ) {
-		if ( ! is_array( $allow_list ) ) {
-			return $allow_list;
-		}
-		$activitypub_meta_keys = array(
-			Followers::FOLLOWER_META_KEY,
-			'_activitypub_inbox',
-		);
-		return \array_merge( $allow_list, $activitypub_meta_keys );
+		$allow_list[] = Followers::FOLLOWER_META_KEY;
+		$allow_list[] = Following::FOLLOWING_META_KEY;
+
+		return $allow_list;
 	}
 
 	/**