ACF_To_REST_API_Controller::rest_insert PHP Method

        public function rest_insert($object, $request, $creating)
        {
            if ($request instanceof WP_REST_Request && !$this->get_id($request) && $this->get_id($object)) {
                $request->set_param('id', $this->id);
            }
            return $this->update_item($request);
        }