code: func (a *AdmissionOptions) Validate() []error {
  	if a == nil {
  		return nil
  	}
  	errs := []error{}
  	if a.PluginNames != nil &&
  		(a.GenericAdmission.EnablePlugins != nil || a.GenericAdmission.DisablePlugins != nil) {
  		errs = append(errs, fmt.Errorf("admission-control and enable-admission-plugins/disable-admission-plugins flags are mutually exclusive"))
  	}
  
  	registeredPlugins := sets.NewString(a.GenericAdmission.Plugins.Registered()...)
  	for _, name := range a.PluginNames {
  		if !registeredPlugins.Has(name) {
  			errs = append(errs, fmt.Errorf("admission-control plugin %q is unknown", name))
  		}
  	}
  
  	errs = append(errs, a.GenericAdmission.Validate()...)
  
  	return errs
  }
docs: // Validate verifies flags passed to kube-apiserver AdmissionOptions.
  // Kube-apiserver verifies PluginNames and then call generic AdmissionOptions.Validate.