v3: refactor domain protocols to a model method

Previously this was implemented on the presenter. This commit moves
the method to the domain model object to be more accessible.

[#172512289]

Co-authored-by: Sarah Weinstein <sweinstein@pivotal.io>
Co-authored-by: Belinda Liu <bliu@pivotal.io>

Author: sweinstein22

app/models/runtime/domain.rb

@@ -143,6 +143,16 @@ def in_suspended_org?
       false
     end
 
+    def protocols
+      return ['http'] if self.private?
+
+      # If Kubernetes is enabled that implies that we are using istio, not the routing API
+      k8s_enabled = !!Config.config.get(:kubernetes, :host_url)
+      return ['tcp'] if !k8s_enabled && self.router_group_guid
+
+      ['http']
+    end
+
     private
 
     def validate_change_owning_organization(organization)

app/presenters/v3/domain_presenter.rb

@@ -24,7 +24,7 @@ def to_hash
         name: domain.name,
         internal: domain.internal,
         router_group: hashified_router_group(domain.router_group_guid),
-        supported_protocols: protocols,
+        supported_protocols: domain.protocols,
         metadata: {
           labels: hashified_labels(domain.labels),
           annotations: hashified_annotations(domain.annotations),
@@ -59,13 +59,13 @@ def domain
       @resource
     end
 
-    def protocols
-      # If Kubernetes is enabled that implies that we are using istio
-      k8s_enabled = !VCAP::CloudController::Config.config.get(:kubernetes, :host_url).blank?
-      return ['tcp'] if !k8s_enabled && domain.router_group_guid
+    # def protocols
+    #   # If Kubernetes is enabled that implies that we are using istio
+    #   k8s_enabled = !VCAP::CloudController::Config.config.get(:kubernetes, :host_url).blank?
+    #   return ['tcp'] if !k8s_enabled && domain.router_group_guid
 
-      return ['http']
-    end
+    #   return ['http']
+    # end
 
     def hashified_router_group(router_group_guid)
       router_group_guid ? { guid: router_group_guid } : nil