WP_REST_Posts_Controller::check_is_post_type_allowed PHP Method

    protected function check_is_post_type_allowed($post_type)
    {
        if (!is_object($post_type)) {
            $post_type = get_post_type_object($post_type);
        }
        if (!empty($post_type) && !empty($post_type->show_in_rest)) {
            return true;
        }
        return false;
    }