wp-includes/rest-api/endpoints/class-wp-rest-widgets-controller.php:507Looks for "lost" widgets once per request.
protected function retrieve_widgets() { if ( ! $this->widgets_retrieved ) { retrieve_widgets(); $this->widgets_retrieved = true; } }Introduced in 5.9.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/rest-api/endpoints/class-wp-rest-widgets-controller.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.