code: func (gServer *GRPCServer) AppendClientRootCAs(clientRoots [][]byte) error {
  	gServer.lock.Lock()
  	defer gServer.lock.Unlock()
  	for _, clientRoot := range clientRoots {
  		err := gServer.appendClientRootCA(clientRoot)
  		if err != nil {
  			return err
  		}
  	}
  	return nil
  }
docs: // AppendClientRootCAs appends PEM-encoded X509 certificate authorities to
  // the list of authorities used to verify client certificates