clone := o
	if o.TLS.Alpn != nil {
		clone.TLS.Alpn = make([]string, len(o.TLS.Alpn))
		copy(clone.TLS.Alpn, o.TLS.Alpn)
	}
	return clone
}

// FillDefaults fills out any defaults that haven't been explicitly specified.
func (o *CallOptions) FillDefaults() error {
	// Fill in the address if not set.
	if err := o.fillAddress(); err != nil {
		return err
	}

		f: forwarder.New(),
	}
}

func (c *Caller) Close() error {
	return c.f.Close()
}

func (c *Caller) CallEcho(from echo.Caller, opts echo.CallOptions) (echo.CallResult, error) {
	if err := opts.FillDefaults(); err != nil {
		return echo.CallResult{}, err
	}

	send := func(req *proto.ForwardEchoRequest) (echoclient.Responses, error) {
		ctx, cancel := context.WithTimeout(context.Background(), opts.Timeout)

		protocols:   protocols,
	}
}

// ForwardEcho sends the requests and collect the responses.
func (i *Instance) ForwardEcho(ctx context.Context, cfg *Config) (*proto.ForwardEchoResponse, error) {
	if err := cfg.fillDefaults(); err != nil {
		return nil, err
	}

	// Lookup the protocol.
	p := i.protocolMap[cfg.scheme]
	if p == nil {
		return nil, fmt.Errorf("no protocol handler found for scheme %s", cfg.scheme)
	}

	}
	c.Configs = func() []echo.Config {
		var out []echo.Config
		if existing != nil {
			out = append(out, existing()...)
		}
		return append(out, configs...)
	}
	return c
}

func (c *Config) fillDefaults(ctx resource.Context) error {
	// Create the namespaces concurrently.
	g, _ := errgroup.WithContext(context.TODO())

	if c.Echos == nil {
		c.Echos = &Echos{}
	}

	if c.Configs == nil {

}

func (f fakeInstance) PortForName(name string) echo.Port {
	return f.Config().Ports.MustForName(name)
}

func (f fakeInstance) Config() echo.Config {
	cfg := echo.Config(f)
	_ = cfg.FillDefaults(nil)
	return cfg
}

func (f fakeInstance) ServiceName() string {
	return f.Config().Service
}

func (f fakeInstance) NamespaceName() string {
	return f.Config().NamespaceName()
}

	Sni string

	// CallMode describes the type of call to make.
	CallMode CallMode

	CustomListenerValidations []CustomFilterChainValidation

	MtlsSecretConfigName string
}

func (c Call) FillDefaults() Call {
	if c.Headers == nil {
		c.Headers = http.Header{}
	}
	if c.HostHeader != "" {
		c.Headers["Host"] = []string{c.HostHeader}
	}
	// For simplicity, set SNI automatically for TLS traffic.

	hboneClientConfig    func(info *tls.CertificateRequestInfo) (*tls.Certificate, error)
	hboneHeaders         http.Header
	proxyProtocolVersion int
	previousResponse     *http.Response
}

func (c *Config) fillDefaults() error {
	c.checkRedirect = checkRedirectFunc(c.Request)
	c.timeout = common.GetTimeout(c.Request)
	c.count = common.GetCount(c.Request)
	c.headers = common.GetHeaders(c.Request)

	if iopYaml != "" {
		data = Indent(iopYaml, "  ")
	}

	return fmt.Sprintf(`
apiVersion: install.istio.io/v1alpha1
kind: IstioOperator
spec:
%s
`, data)
}

func (c *Config) fillDefaults(ctx resource.Context) {
	if ctx.AllClusters().IsExternalControlPlane() {
		c.PrimaryClusterIOPFile = IntegrationTestExternalIstiodPrimaryDefaultsIOP
		c.ConfigClusterIOPFile = IntegrationTestExternalIstiodConfigDefaultsIOP

}

func (f fakeInstance) PortForName(name string) echo.Port {
	return f.Config().Ports.MustForName(name)
}

func (f fakeInstance) Config() echo.Config {
	cfg := echo.Config(f)
	_ = cfg.FillDefaults(nil)
	return cfg
}

func (f fakeInstance) ServiceName() string {
	return f.Config().Service
}

func (f fakeInstance) NamespaceName() string {
	return f.Config().NamespaceName()
}

func (b *builder) With(i *echo.Instance, cfg echo.Config) Builder {
	if b.ctx.Settings().SkipWorkloadClassesAsSet().Contains(cfg.WorkloadClass()) {
		return b
	}

	cfg = cfg.DeepCopy()
	if err := cfg.FillDefaults(b.ctx); err != nil {
		b.errs = multierror.Append(b.errs, err)
		return b
	}

	shouldSkip := b.ctx.Settings().Skip(cfg.WorkloadClass())
	if shouldSkip {
		return b
	}