code: func (opts *Options) Validate() error {
  	if _, found := opts.Tags[GUIDKey]; found {
  		return errInvalidGUIDKey
  	}
  
  	if len(opts.Collector.CustomCACertFile) != 0 {
  		if _, err := os.Stat(opts.Collector.CustomCACertFile); os.IsNotExist(err) {
  			return err
  		}
  	}
  	return nil
  }
docs: // Validate checks that all required fields are set, and no options are incorrectly
  // configured.