code: func (e *execStreamerBuilder) Build() (ExecStreamer, error) {
  	if e.d.ExecutorName == "" {
  		return nil, errors.New("ExecStreamerBuilder requires ExecutorName to be non-empty")
  	}
  	if e.d.Exe == "" {
  		return nil, errors.New("ExecStreamerBuilder requires Exe to be non-empty")
  	}
  	if e.d.StdoutWriter == nil {
  		e.d.StdoutWriter = ioutil.Discard
  	}
  	if e.d.StderrWriter == nil {
  		e.d.StderrWriter = ioutil.Discard
  	}
  
  	return e.d, nil
  }
docs: //Build will validate the set properties and return a ExecStreamer