Index: /trunk/src/wp-includes/class-wp-view-config-data.php
===================================================================
--- /trunk/src/wp-includes/class-wp-view-config-data.php	(revision 62832)
+++ /trunk/src/wp-includes/class-wp-view-config-data.php	(revision 62833)
@@ -160,8 +160,10 @@
 		 *
 		 * A change that declares an unsupported schema version is rejected and does
-		 * not alter anything. Callbacks mutate the container in place, so there is no
-		 * need to return it; any returned value is ignored. Callbacks must not replace
-		 * the container with a different value, as later callbacks receive whatever the
-		 * the previous one returned.
+		 * not alter anything. As with any filter, each callback's return value is
+		 * passed to the next callback as `$data`, so callbacks must return the
+		 * container they received: a callback that returns nothing, or any other
+		 * value, hands that result to every callback hooked at a later priority
+		 * instead of the container. Since the write methods return the container,
+		 * a callback can end with `return $data->merge( $patch, $version );`.
 		 *
 		 * @since 7.1.0