In the third snippet of the example on https://www.pulumi.com/docs/intro/concepts/stack/#stackreferences, the C# code has an apparently-redundant

Apply(v => v.ToString())

. None of the other languages have that. Is it neccessary? If it is, why?

Yes, it is necessary. In the k8s ProviderArgs, the KubeConfig property is string. With no explicit "ToString" call in the Apply function you'll end up with a kubeConfig type of Output<object> and a compiler error. ``````

I use the following output extensions:

public static class OutputExtensions
{
    public static Output<T> As<T>(this Output<object> output) => output.Apply(x => (T)x);

    public static Output<Resource> AsResource<T>(this Output<T> output) where T : Resource => output.Apply(x => (Resource)x);

    public static Output<T> WhenRun<T>(this Output<T> output, Func<T, Task> func) =>
        !Deployment.Instance.IsDryRun ? output.Apply(async value => { await func(value); return value; }) : output;
}

Then that line becomes:

var kubeConfig = cluster.RequireOutput("KubeConfig").As<string>();