code: func RunOptionalJoinNodeChecks(execer utilsexec.Interface, cfg *kubeadmapi.ClusterConfiguration, ignorePreflightErrors sets.String) error {
  	checks := []Checker{}
  
  	// Check if IVPS kube-proxy mode is supported
  	if cfg.ComponentConfigs.KubeProxy != nil && cfg.ComponentConfigs.KubeProxy.Mode == ipvsutil.IPVSProxyMode {
  		checks = append(checks, IPVSProxierCheck{exec: execer})
  	}
  
  	return RunChecks(checks, os.Stderr, ignorePreflightErrors)
  }
docs: // RunOptionalJoinNodeChecks executes all individual, applicable to node configuration dependant checks