code: func (s *DeprecatedInsecureServingOptionsWithLoopback) ApplyTo(insecureServingInfo **server.DeprecatedInsecureServingInfo, loopbackClientConfig **rest.Config) error {
  	if s == nil || s.DeprecatedInsecureServingOptions == nil || insecureServingInfo == nil {
  		return nil
  	}
  
  	if err := s.DeprecatedInsecureServingOptions.ApplyTo(insecureServingInfo); err != nil {
  		return err
  	}
  
  	if *insecureServingInfo == nil || loopbackClientConfig == nil {
  		return nil
  	}
  
  	secureLoopbackClientConfig, err := (*insecureServingInfo).NewLoopbackClientConfig()
  	switch {
  	// if we failed and there's no fallback loopback client config, we need to fail
  	case err != nil && *loopbackClientConfig == nil:
  		return err
  
  		// if we failed, but we already have a fallback loopback client config (usually insecure), allow it
  	case err != nil && *loopbackClientConfig != nil:
  
  	default:
  		*loopbackClientConfig = secureLoopbackClientConfig
  	}
  
  	return nil
  }
docs: // ApplyTo fills up serving information in the server configuration.