Implements: https://github.com/kubernetes/design-proposals-archive/blob/main/api-machinery/thirdpartyresources.md

It provides an API for registering CustomResourceDefinitions.

This API server provides the implementation for CustomResourceDefinitions which is included as delegate server inside of kube-apiserver.

HEAD of this repo will match HEAD of k8s.io/apiserver, k8s.io/apimachinery, and k8s.io/client-go.

apiextensions-apiserver is synced from https://github.com/kubernetes/kubernetes/blob/master/staging/src/k8s.io/apiextensions-apiserver. Code changes are made in that location, merged into k8s.io/kubernetes and later synced here.