code: func (o *CSRSigningControllerOptions) ApplyTo(cfg *csrsigningconfig.CSRSigningControllerConfiguration) error {
  	if o == nil {
  		return nil
  	}
  
  	cfg.ClusterSigningCertFile = o.ClusterSigningCertFile
  	cfg.ClusterSigningKeyFile = o.ClusterSigningKeyFile
  	cfg.ClusterSigningDuration = o.ClusterSigningDuration
  
  	return nil
  }
docs: // ApplyTo fills up CSRSigningController config with options.