code: func ValidateKubeProxyConfiguration(internalcfg *kubeadmapi.ClusterConfiguration, _ *field.Path) field.ErrorList {
  	allErrs := field.ErrorList{}
  	if internalcfg.ComponentConfigs.KubeProxy == nil {
  		return allErrs
  	}
  	return proxyvalidation.Validate(internalcfg.ComponentConfigs.KubeProxy)
  }
docs: // ValidateKubeProxyConfiguration validates proxy configuration and collects all encountered errors