Some notes:

• I just added a new gke auth to my .kube/config. Neither the access token, nor the expiry date, were written to the file. After using kubectl (version 1.16), there was still no access token or expiry date fields. So, my guess is that kubectl has now changed, it no longer caches the access token in the kube config file, and instead reads it from the gcloud commands cache every time.
• The only thing other than gcloud and kubectl itself that would have touched the config is minikube. That said, I was using quite an old version of minikube until very recently when I upgraded. I just did a test then, when minikube modifies the file, it doesn't mangle the date, but the old version may have been what mangled them.

Anyway, I think I'll modify this PR to not support that weird date format, and instead, if the date fails to parse, or is not there, ignore the access token whether it's there or not, and always use gcloud instead.

For anyone needing this fix now, I've published my fork here:

resolvers += Resolver.bintrayRepo("jroper", "maven")
libraryDependencies += "io.skuber" %% "skuber" % "2.3.0-jroper-1"

This also contains my fix to #268, for which there's no published version containing it yet.

Fixes #301

I was looking for an issue, and didn't even think to look for a PR :) So I prepared a PR to address the optional access-token issue too. Will close it in favor of yours.

Thanks for working on this and for publishing the patched version.

LGTM - thanks. (and also thanks for providing a fork, I plan to get this released "officially" in the next couple of days).