> But I haven't used source generators in C# in at least 10 years, and I honestly don't know why anyone would at this point.

A challenge with .NET web APIs is that it's not possible to detect when interacting with a payload deserialized from JSON whether it's `null` because it was set to `null` or `null` because it was not supplied.

A common way to work around this is to provide a `IsSet` boolean:

    private bool _isNameSet;

    public string? Name { get; set { ...; isNameSet = true; } }

Now you can check if the value is set.

However, you can see how tedious this can get without a source Generator. With a source generator, we simply take nullable partial properties and generate the stub automatically.

    public partial string? Name { get; set; }

Now a single marker attribute will generate as many `Is*Set` properties as needed.

Of course, the other use case is for AOT to avoid reflection by generating the source at runtime.