fix: broken tls in jx preview

fixes #2196

- the `omitempty` json tag was missing from the ExposeControllerConfig struct, which resulted in empty values being present in the extraValues.yaml file - thus overriding valid values from the values.yaml file
- the cmdline flags passed through `jx preview` for the ExposeControllerConfig struct were not used to generate the extraValues.yaml file

pkg/config/helm_values.go

@@ -9,10 +9,10 @@ import (
 
 type ExposeControllerConfig struct {
 	Domain   string `yaml:"domain,omitempty"`
-	Exposer  string `yaml:"exposer"`
-	HTTP     string `yaml:"http"`
-	TLSAcme  string `yaml:"tlsacme"`
-	PathMode string `yaml:"pathMode"`
+	Exposer  string `yaml:"exposer,omitempty"`
+	HTTP     string `yaml:"http,omitempty"`
+	TLSAcme  string `yaml:"tlsacme,omitempty"`
+	PathMode string `yaml:"pathMode,omitempty"`
 }
 type ExposeController struct {
 	Config      ExposeControllerConfig `yaml:"config,omitempty"`

pkg/jx/cmd/preview.go

@@ -435,12 +435,12 @@ func (o *PreviewOptions) Run() error {
 		return err
 	}
 
+	if o.HelmValuesConfig.ExposeController == nil {
+		o.HelmValuesConfig.ExposeController = &config.ExposeController{}
+	}
+	o.HelmValuesConfig.ExposeController.Config.Domain = domain
 	values := config.PreviewValuesConfig{
-		ExposeController: &config.ExposeController{
-			Config: config.ExposeControllerConfig{
-				Domain: domain,
-			},
-		},
+		ExposeController: o.HelmValuesConfig.ExposeController,
 		Preview: &config.Preview{
 			Image: &config.Image{
 				Repository: repository,