Fix finish_reason logic in Azure AI client streaming response (#6963)

Co-authored-by: weizhang3 <weizhang3@microsoft.com>
Co-authored-by: Eric Zhu <ekzhu@users.noreply.github.com>

Author: 3 people

python/packages/autogen-ext/src/autogen_ext/models/azure/_azure_ai_client.py

@@ -523,6 +523,9 @@ async def create_stream(
             if choice and choice.finish_reason is not None:
                 if isinstance(choice.finish_reason, CompletionsFinishReason):
                     finish_reason = cast(FinishReasons, choice.finish_reason.value)
+                    # Handle special case for TOOL_CALLS finish reason
+                    if choice.finish_reason is CompletionsFinishReason.TOOL_CALLS:
+                        finish_reason = "function_calls"
                 else:
                     if choice.finish_reason in ["stop", "length", "function_calls", "content_filter", "unknown"]:
                         finish_reason = choice.finish_reason  # type: ignore
@@ -554,9 +557,6 @@ async def create_stream(
         if finish_reason is None:
             raise ValueError("No stop reason found")
 
-        if choice and choice.finish_reason is CompletionsFinishReason.TOOL_CALLS:
-            finish_reason = "function_calls"
-
         content: Union[str, List[FunctionCall]]
 
         if len(content_deltas) > 1: