code: func (flag *HostConnectFlag) Spec(c *vim25.Client) types.HostConnectSpec {
  	spec := flag.HostConnectSpec
  
  	if spec.SslThumbprint == "" {
  		spec.SslThumbprint = c.Thumbprint(spec.HostName)
  
  		if spec.SslThumbprint == "" && flag.noverify {
  			var info object.HostCertificateInfo
  			t := c.Transport.(*http.Transport)
  			_ = info.FromURL(&url.URL{Host: spec.HostName}, t.TLSClientConfig)
  			spec.SslThumbprint = info.ThumbprintSHA1
  		}
  	}
  
  	return spec
  }
docs: // Spec attempts to fill in SslThumbprint if empty.
  // First checks GOVC_TLS_KNOWN_HOSTS, if not found and noverify=true then
  // use object.HostCertificateInfo to get the thumbprint.