Automattic\VIP\Performance\Last_Post_Modified::bump_lastpostmodified PHP Method

    public static function bump_lastpostmodified($post)
    {
        self::update_lastpostmodified($post->post_modified_gmt, 'gmt', $post->post_type);
        self::update_lastpostmodified($post->post_modified_gmt, 'server', $post->post_type);
        self::update_lastpostmodified($post->post_modified, 'blog', $post->post_type);
    }