Graph ResyncRequired error can also manifest as resyncRequired (#2688)

The only change is that the first letter is now small.

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- [ ] 🕐 Yes, but in a later PR
- [x] ⛔ No

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

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#### Test Plan

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- [x] ⚡ Unit test
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src/internal/connector/graph/errors.go

@@ -6,6 +6,7 @@ import (
 	"net/http"
 	"net/url"
 	"os"
+	"strings"
 
 	"github.com/microsoftgraph/msgraph-sdk-go/models/odataerrors"
 	"github.com/pkg/errors"
@@ -23,7 +24,7 @@ const (
 	errCodeItemNotFound                = "ErrorItemNotFound"
 	errCodeItemNotFoundShort           = "itemNotFound"
 	errCodeEmailFolderNotFound         = "ErrorSyncFolderNotFound"
-	errCodeResyncRequired              = "ResyncRequired"
+	errCodeResyncRequired              = "ResyncRequired" // alt: resyncRequired
 	errCodeSyncFolderNotFound          = "ErrorSyncFolderNotFound"
 	errCodeSyncStateNotFound           = "SyncStateNotFound"
 	errCodeResourceNotFound            = "ResourceNotFound"
@@ -187,7 +188,12 @@ func hasErrorCode(err error, codes ...string) bool {
 		return false
 	}
 
-	return slices.Contains(codes, *oDataError.GetError().GetCode())
+	lcodes := []string{}
+	for _, c := range codes {
+		lcodes = append(lcodes, strings.ToLower(c))
+	}
+
+	return slices.Contains(lcodes, strings.ToLower(*oDataError.GetError().GetCode()))
 }
 
 // ErrData is a helper function that extracts ODataError metadata from

src/internal/connector/graph/errors_test.go

@@ -104,6 +104,17 @@ func (suite *GraphErrorsUnitSuite) TestIsErrInvalidDelta() {
 			err:    odErr(errCodeResyncRequired),
 			expect: assert.True,
 		},
+		// next two tests are to make sure the checks are case insensitive
+		{
+			name:   "resync-required oDataErr camelcase",
+			err:    odErr("resyncRequired"),
+			expect: assert.True,
+		},
+		{
+			name:   "resync-required oDataErr lowercase",
+			err:    odErr("resyncrequired"),
+			expect: assert.True,
+		},
 	}
 	for _, test := range table {
 		suite.Run(test.name, func() {