[BUG] Attempting to use SetNewMaxCompletionTokensPropertyEnabled in a new ChatCompletionOptions throws.

[RogerBarreto]

Library name and version

Azure.AI.OpenAI 2.2.0-beta.1

Describe the bug

If we instantiate ChatCompletionOptions without enforcing a deserialization first, the additionalProperties internal field is not initialized (=null) and attempting to run the SetNewMaxCompletionTokensPropertyEnable extension method throws a ArgumentNullException.

Reproduction

var options1 = new ChatCompletionOptions();

// Throws Argument Null Exception.
options1.SetNewMaxCompletionTokensPropertyEnabled(true);

Exception

Workaround (Proving the serialization point above)

ChatCompletionOptions options = ModelReaderWriter.Read<ChatCompletionOptions>(BinaryData.FromString("{}")!)!;

// This won't throw
options.SetNewMaxCompletionTokensPropertyEnabled(true);

Expected behavior

No errors.

Actual behavior

Argument Null Exception

Reproduction Steps

var options1 = new ChatCompletionOptions();
options1.SetNewMaxCompletionTokensPropertyEnabled(true);

Environment

.NET SDK:
Version: 9.0.103
Commit: 96da45d427
Workload version: 9.0.100-manifests.ea610b94
MSBuild version: 17.12.24+90b52dda6

Runtime Environment:
OS Name: Windows
OS Version: 10.0.26100
OS Platform: Windows
RID: win-x64
Base Path: C:\Program Files\dotnet\sdk\9.0.103\

[github-actions]

Thanks for the feedback! We are routing this to the appropriate team for follow-up. cc @jpalvarezl @ralph-msft @trrwilson.