structs: remove EnterpriseMeta.GetNamespace

I added this recently without realizing that the method already existed and was named
NamespaceOrEmpty. Replace all calls to GetNamespace with NamespaceOrEmpty or NamespaceOrDefault
as appropriate.

agent/cache-types/streaming_health_services.go

@@ -74,7 +74,7 @@ func (c *StreamingHealthServices) Fetch(opts cache.FetchOptions, req cache.Reque
 			Token:      srvReq.Token,
 			Datacenter: srvReq.Datacenter,
 			Index:      index,
-			Namespace:  srvReq.EnterpriseMeta.GetNamespace(),
+			Namespace:  srvReq.EnterpriseMeta.NamespaceOrEmpty(),
 		}
 		if srvReq.Connect {
 			req.Topic = pbsubscribe.Topic_ServiceHealthConnect

agent/cache-types/streaming_health_services_test.go

@@ -229,7 +229,7 @@ func requireResultsSame(t *testing.T, want, got *structs.IndexedCheckServiceNode
 // without duplicating the tests.
 func getNamespace(ns string) string {
 	meta := structs.NewEnterpriseMeta(ns)
-	return meta.GetNamespace()
+	return meta.NamespaceOrEmpty()
 }
 
 func TestOrderingConsistentWithMemDb(t *testing.T) {

agent/consul/state/catalog_events.go

@@ -41,7 +41,7 @@ func (e EventPayloadCheckServiceNode) MatchesKey(key, namespace string) bool {
 	if e.key != "" {
 		name = e.key
 	}
-	ns := e.Value.Service.EnterpriseMeta.GetNamespace()
+	ns := e.Value.Service.EnterpriseMeta.NamespaceOrDefault()
 	return (key == "" || key == name) && (namespace == "" || namespace == ns)
 }
 

agent/rpc/subscribe/subscribe.go

@@ -95,7 +95,7 @@ func toStreamSubscribeRequest(req *pbsubscribe.SubscribeRequest, entMeta structs
 		Key:       req.Key,
 		Token:     req.Token,
 		Index:     req.Index,
-		Namespace: entMeta.GetNamespace(),
+		Namespace: entMeta.NamespaceOrEmpty(),
 	}
 }
 

agent/structs/structs_oss.go

@@ -74,11 +74,6 @@ func (_ *EnterpriseMeta) FillAuthzContext(_ *acl.AuthorizerContext) {}
 
 func (_ *EnterpriseMeta) Normalize() {}
 
-// GetNamespace always returns the empty string.
-func (_ *EnterpriseMeta) GetNamespace() string {
-	return ""
-}
-
 // FillAuthzContext stub
 func (_ *DirEntry) FillAuthzContext(_ *acl.AuthorizerContext) {}