code: func (r *TunnelConnectionV2) Check() error {
  	if r.Version == "" {
  		return trace.BadParameter("missing version")
  	}
  	if strings.TrimSpace(r.Spec.ClusterName) == "" {
  		return trace.BadParameter("empty cluster name")
  	}
  
  	if len(r.Spec.ProxyName) == 0 {
  		return trace.BadParameter("missing parameter proxy name")
  	}
  
  	return nil
  }
docs: // Check returns nil if all parameters are good, error otherwise