code: func (ref *Config) ValidateAsyncProducerConfig() error {
  	if ref.Brokers == nil {
  		return errors.New("invalid Brokers - one or more brokers must be specified")
  	}
  	if ref.SendSuccess && ref.SuccessChan == nil {
  		return errors.New("success channel not specified")
  	}
  	if ref.SendError && ref.ErrorChan == nil {
  		return errors.New("error channel not specified")
  	}
  	return ref.ProducerConfig().Validate()
  }
docs: // ValidateAsyncProducerConfig validates config for an Async Producer