code: func cleanRetryJoin(a string) string {
  	var fields []string
  	for _, f := range strings.Fields(a) {
  		if isSecret(f) {
  			kv := strings.SplitN(f, "=", 2)
  			fields = append(fields, kv[0]+"=hidden")
  		} else {
  			fields = append(fields, f)
  		}
  	}
  	return strings.Join(fields, " ")
  }
docs: // cleanRetryJoin sanitizes the go-discover config strings key=val key=val...
  // by scrubbing the individual key=val combinations.