Having used integer primary keys for many projects, I've only recently switched over to using UUIDs on a few projects about a little less than a year ago. In the switch, an old solution I've often used for checking if an object exists, or is being created, has become obsolete.
More often than not I've worked on projects that, to my dismay, had limited to no documentation. Some projects didn't even include README files (fun experience when you're trying to get a custom project running). You can't always control the code that you inherit, whether it's legacy code in your own organization or an open source project. You can however make everyone else's lives easier by including some form of documentation.