Graph.Drive.Item.Content returns null if the file is empty

Describe the bug

Graph.Drive.Item.Content is to be used to return a stream of the file content, however if the file is empty it returns null - this is unexpected because an empty file (stream with length zero) is different from null - happy to be directed to any doco which contradicts this for Graph purposes.

Expected behavior

Should return a stream with length zero

How to reproduce

Upload an empty file and try to download its contents using code like this:

            var content = await graphClient
                .Drives["b!C6YVIzpT60SYqdpHCYpAZXQj2FA-LzVJhxb5VG0bjuh5Q7qKO0dqTpssSrUI12kI"]
                .Items["01ACRBDKP5P323XRKICFA2XSPOZVLGJFSW"]
                .Content
                .GetAsync();

content is null

SDK Version

No response

Latest version known to work for scenario above?

No response

Known Workarounds

No response

Debug output

</details>


### Configuration

_No response_

### Other information

_No response_

Start by running the provided Graph.Drive.Item.Content.GetAsync reproduction with an uploaded empty file and inspect the returned content. Determine whether the SDK or Graph response produces null, then verify the result against the expected zero-length stream behavior. Done means empty files return a non-null stream with length zero.