Alternative way to handle 2-level calendars hierarchy (#2397)

## Description

All calendars except the default are nested under a "Other Calendars" folder. Having a non-default calendar named the same as the default calendar does not cause problems when fetching the default calendar by name. Only the default calendar will be returned in that situation.

This fixes the bug where we had multiple collections for the same path but representing different folders.

Also updates the restore execution path to handle the new nested folder structure.

Backup, incremental backup, and restore flows tested manually

## Does this PR need a docs update or release note?

- [x] ✅ Yes, it's included
- [ ] 🕐 Yes, but in a later PR
- [ ] ⛔ No 

## Type of change

- [ ] 🌻 Feature
- [x] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [ ] 🤖 Test
- [ ] 💻 CI/Deployment
- [ ] 🧹 Tech Debt/Cleanup

## Issue(s)

* #2388

## Test Plan

- [x] 💪 Manual
- [ ] ⚡ Unit test
- [ ] 💚 E2E

CHANGELOG.md

@@ -16,6 +16,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Add `--restore-permissions` flag to toggle restoration of OneDrive permissions
 - Add versions to backups so that we can understand/handle older backup formats
 
+### Fixed
+- Backing up a calendar that has the same name as the default calendar
+
 ### Known Issues
 
 - When the same user has permissions to a file and the containing

src/internal/connector/exchange/container_resolver_test.go

@@ -501,10 +501,11 @@ func (suite *FolderCacheIntegrationSuite) TestCreateContainerDestination() {
 		directoryCaches = make(map[path.CategoryType]graph.ContainerResolver)
 		folderName      = tester.DefaultTestRestoreDestination().ContainerName
 		tests           = []struct {
-			name      string
-			pathFunc1 func(t *testing.T) path.Path
-			pathFunc2 func(t *testing.T) path.Path
-			category  path.CategoryType
+			name         string
+			pathFunc1    func(t *testing.T) path.Path
+			pathFunc2    func(t *testing.T) path.Path
+			category     path.CategoryType
+			folderPrefix string
 		}{
 			{
 				name:     "Mail Cache Test",
@@ -587,6 +588,7 @@ func (suite *FolderCacheIntegrationSuite) TestCreateContainerDestination() {
 					require.NoError(t, err)
 					return aPath
 				},
+				folderPrefix: calendarOthersFolder,
 			},
 		}
 	)
@@ -617,8 +619,9 @@ func (suite *FolderCacheIntegrationSuite) TestCreateContainerDestination() {
 			_, err = resolver.IDToPath(ctx, secondID)
 			require.NoError(t, err)
 
-			_, ok := resolver.PathInCache(folderName)
-			require.True(t, ok)
+			p := stdpath.Join(test.folderPrefix, folderName)
+			_, ok := resolver.PathInCache(p)
+			require.True(t, ok, "looking for path in cache: %s", p)
 		})
 	}
 }

src/internal/connector/exchange/data_collections_test.go

@@ -537,9 +537,9 @@ func (suite *DataCollectionsIntegrationSuite) TestEventsSerializationRegression(
 		},
 		{
 			name:     "Birthday Calendar",
-			expected: "Birthdays",
+			expected: calendarOthersFolder + "/Birthdays",
 			scope: selectors.NewExchangeBackup(users).EventCalendars(
-				[]string{"Birthdays"},
+				[]string{calendarOthersFolder + "/Birthdays"},
 				selectors.PrefixMatch(),
 			)[0],
 		},

src/internal/connector/exchange/event_calendar_cache.go

@@ -64,7 +64,15 @@ func (ecc *eventCalendarCache) Populate(
 		return errors.Wrap(err, "initializing")
 	}
 
-	err := ecc.enumer.EnumerateContainers(ctx, ecc.userID, "", ecc.addFolder)
+	err := ecc.enumer.EnumerateContainers(
+		ctx,
+		ecc.userID,
+		"",
+		func(cf graph.CacheFolder) error {
+			cf.SetPath(path.Builder{}.Append(calendarOthersFolder, *cf.GetDisplayName()))
+			return ecc.addFolder(cf)
+		},
+	)
 	if err != nil {
 		return errors.Wrap(err, "enumerating containers")
 	}
@@ -83,7 +91,7 @@ func (ecc *eventCalendarCache) AddToCache(ctx context.Context, f graph.Container
 		return errors.Wrap(err, "validating container")
 	}
 
-	temp := graph.NewCacheFolder(f, path.Builder{}.Append(*f.GetDisplayName()))
+	temp := graph.NewCacheFolder(f, path.Builder{}.Append(calendarOthersFolder, *f.GetDisplayName()))
 
 	if err := ecc.addFolder(temp); err != nil {
 		return errors.Wrap(err, "adding container")

src/internal/connector/exchange/exchange_vars.go

@@ -38,4 +38,5 @@ const (
 	rootFolderAlias      = "msgfolderroot"
 	DefaultContactFolder = "Contacts"
 	DefaultCalendar      = "Calendar"
+	calendarOthersFolder = "Other Calendars"
 )

src/internal/connector/exchange/service_restore.go

@@ -645,7 +645,11 @@ func establishEventsRestoreLocation(
 	user string,
 	isNewCache bool,
 ) (string, error) {
-	cached, ok := ecc.PathInCache(folders[0])
+	// Need to prefix with the "Other Calendars" folder so lookup happens properly.
+	cached, ok := ecc.PathInCache(path.Builder{}.Append(
+		calendarOthersFolder,
+		folders[0],
+	).String())
 	if ok {
 		return cached, nil
 	}