Members@delta is empty during initial group delta sync under AdditionalData

[Vijaymahantesh-bit]

Describe the bug

After updating the MS Graph SDK from 5.37 to 5.105. Members@delta is empty during initial group delta sync. Below is the code snippet & response attached for both versions.

Expected behavior

Expecting members delta under Additional data as shown
"AdditionalData": { "members@delta": [ { "@odata.type": "#microsoft.graph.user", "id": "<Guid>" }, { "@odata.type": "#microsoft.graph.user", "id": "<Guid>" }, { "@odata.type": "#microsoft.graph.user", "id": "<Guid>" } ] },

with latest SDK getting the empty response as show below
"AdditionalData": { "members@delta": {} },

How to reproduce

Code used to reproduce.

private static async Task DebugGroupMembersSyncWorkflow(GraphServiceClient client, string groupId = null!, string deltaLink = null!)
    {
        var nextLink = deltaLink;
        do
        {
            var deltaResponse = string.IsNullOrEmpty(nextLink)
                ? await GetDeltaResponse(client, groupId).ConfigureAwait(false)
                : await GetDeltaResponse(client, new Uri(nextLink)).ConfigureAwait(false);

            nextLink = deltaResponse.NextLink;
            deltaLink = deltaResponse.DeltaLink;

            if (!string.IsNullOrEmpty(nextLink))
            {
                var memberCount = deltaResponse.MemberIds.Count();
                var removedCount = deltaResponse.RemovedMemberIds.Count();
                var hasNextLink = !string.IsNullOrEmpty(deltaResponse.NextLink);

                Console.WriteLine($"MemberIds count: {memberCount}, RemovedMemberIds count: {removedCount}, HasNextLink: {hasNextLink}");
            }

            Console.WriteLine($"HasNextLink: {!string.IsNullOrEmpty(deltaResponse.NextLink)}, HasDeltaLink: {!string.IsNullOrEmpty(deltaResponse.DeltaLink)}");
            
        } while (!string.IsNullOrEmpty(nextLink));

        Console.WriteLine($"Completed group members delta sync and has DeltaSyncLink {!string.IsNullOrEmpty(deltaLink)}");
        Console.WriteLine("Would you want to run delta sync again using the delta link? (y/n): ");
        var input = Console.ReadLine();

        if(input == "y")
        {
            await DebugGroupMembersSyncWorkflow(client, deltaLink: deltaLink);
        }
    }

    private static async Task<GroupMembersDeltaResponse> GetDeltaResponse(GraphServiceClient client, string groupId)
    {
        var deltaResponse = await client.Groups.Delta.GetAsDeltaGetResponseAsync(
            config =>
            {
                config.QueryParameters.Filter = $"id eq '{groupId}'";
                config.QueryParameters.Select = ["displayName", "members"];
            },
            CancellationToken.None).ConfigureAwait(false);

        string serlializedResponse = System.Text.Json.JsonSerializer.Serialize(deltaResponse);

        return deltaResponse!.GetGroupMembersDelta();
    }

    private static async Task<GroupMembersDeltaResponse> GetDeltaResponse(GraphServiceClient client, Uri url)
    {
        var deltaResponse = await client.Groups.Delta
                                .WithUrl(url.ToString())
                                .GetAsDeltaGetResponseAsync(cancellationToken: CancellationToken.None).ConfigureAwait(false);

        ArgumentNullException.ThrowIfNull(deltaResponse, nameof(deltaResponse));

        return deltaResponse.GetGroupMembersDelta();
    }

    private static GroupMembersDeltaResponse GetGroupMembersDelta(this Microsoft.Graph.Groups.Delta.DeltaGetResponse deltaGetResponse)
    {
        ArgumentNullException.ThrowIfNull(deltaGetResponse, nameof(deltaGetResponse));

        var group = deltaGetResponse.Value?.FirstOrDefault();
        if (group == null)
        {
            return new GroupMembersDeltaResponse
            {
                NextLink = deltaGetResponse.OdataNextLink ?? string.Empty,
                DeltaLink = deltaGetResponse.OdataDeltaLink ?? string.Empty,
            };
        }

        var groupMembersDeltaResponse = new GroupMembersDeltaResponse
        {
            GroupId = group.Id!,
            GroupName = group.DisplayName!,
            MemberIds = Enumerable.Empty<string>(),
            RemovedMemberIds = Enumerable.Empty<string>(),
            NextLink = deltaGetResponse.OdataNextLink!,
            DeltaLink = deltaGetResponse.OdataDeltaLink!,
        };

        if (group.AdditionalData.TryGetValue("members@delta", out var membersDelta) && membersDelta is JsonElement membersDeltaElement)
        {
            var members = System.Text.Json.JsonSerializer.Deserialize<IEnumerable<GraphUserRef>>(membersDeltaElement.GetRawText());
            groupMembersDeltaResponse.MemberIds = members?.Where(x => x.Removed == null).Select(x => x.Id) ?? Enumerable.Empty<string>();
            groupMembersDeltaResponse.RemovedMemberIds = members?.Where(x => x.Removed != null).Select(x => x.Id) ?? Enumerable.Empty<string>();
        }

        return groupMembersDeltaResponse;
    }
}


public record GraphUserRef(
    [JsonPropertyName("@odata.type")] string ODataType,
    [JsonPropertyName("id")] string Id,
    [JsonPropertyName("@removed")] string? Removed
);

public class GroupMembersDeltaResponse
{
    /// <summary>
    /// Gets or sets the unique identifier of the group.
    /// </summary>
    public string GroupId { get; set; } = string.Empty;

    /// <summary>
    /// Gets or sets the name of the group.
    /// </summary>
    public string GroupName { get; set; } = string.Empty;

    /// <summary>
    /// Gets or sets the member IDs of the group.
    /// </summary>
    public IEnumerable<string> MemberIds { get; set; } = Array.Empty<string>();

    /// <summary>
    /// Gets or sets the removed member IDs of the group.
    /// </summary>
    public IEnumerable<string> RemovedMemberIds { get; set; } = Array.Empty<string>();

    /// <summary>
    /// Gets or sets the next link for pagination.
    /// </summary>
    public string NextLink { get; set; } = string.Empty;

    /// <summary>
    /// Gets or sets the URL that can be used to retrieve changes since the last request.
    /// </summary>
    public string DeltaLink { get; set; } = string.Empty;
}

SDK Version

5.105

Latest version known to work for scenario above?

5.37

Known Workarounds

Downgrading the package works for now.

Debug output

Click to expand log

```

</details>


### Configuration

_No response_

### Other information

_No response_

[MIchaelMainer]

Take the URL for the request that resulted in: "AdditionalData": { "members@delta": {} }

Can you submit that request URL via Graph Explorer (or any other web dev request tool) and show us what the AdditionalData contents contains?

[Vijaymahantesh-bit]

I was able to intercept http calls which SDK makes for group delta request.

I have attached Request URL, Actual Http response & SDK degenerated response as part of Microsoft.Graph.Groups.Delta.DeltaGetResponse deserialization.

Findings:

1. Used 5.105.0 version for this.
2. Actual http response has members delta list, however same is missing after deserialization as Microsoft.Graph.Groups.Delta.DeltaGetResponse this model.

Request:
GET https://graph.microsoft.com/v1.0/groups/delta()?%24filter=id eq %<GroupId_Guid>%27&%24select=displayName,members

Http Response:

{
"@odata.context": "https://graph.microsoft.com/v1.0/$metadata#groups(displayName,members)",
"@odata.nextLink": "Redacted",
"value": [
{
"displayName": "Redacted",
"id": "",
"members@delta": [
{
"@odata.type": "#microsoft.graph.user",
"id": "Redacted"
},
{
"@odata.type": "#microsoft.graph.user",
"id": "Redacted"
},
{
"@odata.type": "#microsoft.graph.user",
"id": "Redacted"
}
]
}
]
}

Desterilized response from SDK as Microsoft.Graph.Groups.Delta.DeltaGetResponse model.
{
"Value": [
{
"AcceptedSenders": null,
"AllowExternalSenders": null,
"AppRoleAssignments": null,
"AssignedLabels": null,
"AssignedLicenses": null,
"AutoSubscribeNewMembers": null,
"Calendar": null,
"CalendarView": null,
"Classification": null,
"Conversations": null,
"CreatedDateTime": null,
"CreatedOnBehalfOf": null,
"Description": null,
"DisplayName": "Redacted",
"Drive": null,
"Drives": null,
"Events": null,
"ExpirationDateTime": null,
"Extensions": null,
"GroupLifecyclePolicies": null,
"GroupTypes": null,
"HasMembersWithLicenseErrors": null,
"HideFromAddressLists": null,
"HideFromOutlookClients": null,
"IsArchived": null,
"IsAssignableToRole": null,
"IsManagementRestricted": null,
"IsSubscribedByMail": null,
"LicenseProcessingState": null,
"Mail": null,
"MailEnabled": null,
"MailNickname": null,
"MemberOf": null,
"Members": null,
"MembershipRule": null,
"MembershipRuleProcessingState": null,
"MembersWithLicenseErrors": null,
"Onenote": null,
"OnPremisesDomainName": null,
"OnPremisesLastSyncDateTime": null,
"OnPremisesNetBiosName": null,
"OnPremisesProvisioningErrors": null,
"OnPremisesSamAccountName": null,
"OnPremisesSecurityIdentifier": null,
"OnPremisesSyncBehavior": null,
"OnPremisesSyncEnabled": null,
"Owners": null,
"PermissionGrants": null,
"Photo": null,
"Photos": null,
"Planner": null,
"PreferredDataLocation": null,
"PreferredLanguage": null,
"ProxyAddresses": null,
"RejectedSenders": null,
"RenewedDateTime": null,
"ResourceBehaviorOptions": null,
"ResourceProvisioningOptions": null,
"SecurityEnabled": null,
"SecurityIdentifier": null,
"ServiceProvisioningErrors": null,
"Settings": null,
"Sites": null,
"Team": null,
"Theme": null,
"Threads": null,
"TransitiveMemberOf": null,
"TransitiveMembers": null,
"UniqueName": null,
"UnseenCount": null,
"Visibility": null,
"WelcomeMessageEnabled": null,
"DeletedDateTime": null,
"AdditionalData": {
"members@delta": {} // Here it is empty.
},
"BackingStore": {
"InitializationCompleted": false,
"ReturnOnlyChangedValues": false
},
"Id": "",
"OdataType": "#microsoft.graph.group"
}
],
"AdditionalData": {
"@odata.context": "https://graph.microsoft.com/v1.0/$metadata#groups(displayName,members)"
},
"BackingStore": {
"InitializationCompleted": true,
"ReturnOnlyChangedValues": false
},
"OdataDeltaLink": null,
"OdataNextLink": "Redacted"
}