code: func (gServer *GRPCServer) appendClientRootCA(clientRoot []byte) error {
  
  	errMsg := "Failed to append client root certificate(s): %s"
  	//convert to x509
  	certs, subjects, err := pemToX509Certs(clientRoot)
  	if err != nil {
  		return fmt.Errorf(errMsg, err.Error())
  	}
  
  	if len(certs) < 1 {
  		return fmt.Errorf(errMsg, "No client root certificates found")
  	}
  
  	for i, cert := range certs {
  		//first add to the ClientCAs
  		gServer.tlsConfig.ClientCAs.AddCert(cert)
  		//add it to our clientRootCAs map using subject as key
  		gServer.clientRootCAs[subjects[i]] = cert
  	}
  	return nil
  }
docs: // internal function to add a PEM-encoded clientRootCA