Different filter escaping behaviour in batch and direct requests

Describe the bug

I'm trying to find a user and a selection of their properties through their email. Currently I'm building a filter to find said user like so:

• filter: identities/any(id:id/issuer eq ' ' and id/issuerAssignedId eq '{emailAddress}')

For most email addresses, the filtering works as expected for both direct requests using _GraphServiceClient.Users.GetAsync() as well as batch requests and building the requests with _GraphServiceClient.Users.ToGetRequestInformation().

I've noticed that some of our users aren't returned by the batch requests but provide valid responses through a direct request.
The emails have in common that they contain a '+' character, e.g. test+mailPostfix@mail.com. Upon further investigation I've noticed that the Graph API can't handle the '+' character and needs it to be escaped.
Apparently, the filter string is escaped when requesting _GraphServiceClient.Users.GetAsync() but not when using _GraphServiceClient.Users.ToGetRequestInformation() followed by a batch request.

Expected behavior

The filter behaviour should be equal throughout the SDK and not differ between usages. I believe the filter should also be escaped when build a request and sending it through a batch request.

How to reproduce

Assuming I have a list of emails for which I want some B2C properties like the display name.

When I use the the SDK by sending the requests one by one like so, everything works as expected:

var usersResponse = await _GraphServiceClient.Users
            .GetAsync(requestConfig =>
            {
                requestConfig.QueryParameters.Top = 999;
                requestConfig.QueryParameters.Select = ["displayName", "identities", "otherMails", "id"];
                requestConfig.QueryParameters.Filter = $"identities/any(id:id/issuer eq ' ' and id/issuerAssignedId eq '{emailAddress}')";
            }, cancellationToken);

if (usersResponse == null)
{
    return null;
}

var userList = new List<User>();
var pageIterator = PageIterator<User, UserCollectionResponse>.CreatePageIterator(_GraphServiceClient, usersResponse, user =>
{
    userList.Add(user);
    return true;
});
await pageIterator.IterateAsync(cancellationToken);

return userList;

But creating a batch request when the list of email addresses might become bigger creates empty results for emails with a '+' character. The request is built like this:

var batchRequestContent = new BatchRequestContentCollection(_GraphServiceClient);
var requestIdsForEmails = new Dictionary<string, string>();
foreach (var emailAddress in emailAddresses)
{
     var identityRequest = _GraphServiceClient.Users.ToGetRequestInformation(requestConfig =>
     {
          requestConfig.QueryParameters.Select = UserSelections;
          requestConfig.QueryParameters.Filter = $"identities/any(id:id/issuer eq ' ' and id/issuerAssignedId eq '{emailAddress}')"
     });

     var identityRequestId = await batchRequestContent.AddBatchRequestStepAsync(identityRequest);

     requestIdsForEmails.Add(emailAddress, [identityRequestId, otherMailRequestId]);
}
var batchResponse = await _GraphServiceClient.Batch.PostAsync(batchRequestContent, cancellationToken);

var emailsWithUsers = new Dictionary<string, IEnumerable<User>>();
foreach (var emailWithRequestIds in requestIdsForEmails)
{
     try
     {
          var userResponse = await batchResponse.GetResponseByIdAsync<UserCollectionResponse>(emailWithRequestIds.Value);

          emailsWithUsers.Add(emailWithRequestIds.Key, userResponse.Value);
      }
      catch (Exception)
      {
          emailsWithUsers.Add(emailWithRequestIds.Key, []);
      }
}
return emailsWithUsers;

SDK Version

5.59.0

Latest version known to work for scenario above?

No response

Known Workarounds

I've fixed the issue by explicitly escaping the emailAddress before using it in the filter:

var escapedEmail = Uri.EscapeDataString(emailAddress);
var identityRequest = _GraphServiceClient.Users.ToGetRequestInformation(requestConfig =>
{
    requestConfig.QueryParameters.Select = UserSelections;
    requestConfig.QueryParameters.Filter = $"identities/any(id:id/issuer eq ' ' and id/issuerAssignedId eq '{escapedEmail }')"
});

But this creates an odd situation since escaping the emailAddress with a direct request to _GraphServiceClient.Users.GetAsync() breaks the direct request. So I need to handle the email addresses differently which creates a confusing situation in the code base.

Debug output

No response

Configuration

• OS: Windows 11
• architecture x64

Other information

No response

Start by reproducing the difference between Users.GetAsync() and Users.ToGetRequestInformation() in a batch request with an email containing '+'. Compare how the filter is serialized in both paths, and verify completion when equivalent requests return the same user results without requiring different caller-side escaping.