Index: src/wp-includes/meta.php
===================================================================
--- src/wp-includes/meta.php	(revision 33652)
+++ src/wp-includes/meta.php	(working copy)
@@ -480,7 +480,8 @@
 	 *                                     or an array of values.
 	 * @param int               $object_id Object ID.
 	 * @param string            $meta_key  Meta key.
-	 * @param string|array      $single    Meta value, or an array of values.
+	 * @param bool              $single    Whether to return only the first
+	 *                                     value of the specified $meta_key.
 	 */
 	$check = apply_filters( "get_{$meta_type}_metadata", null, $object_id, $meta_key, $single );
 	if ( null !== $check ) {