.NET: Incorrect description on AgentSessionStore.GetSessionAsync regarding "returning null if not found"

[ad-eg-dk]

agent-framework/dotnet/src/Microsoft.Agents.AI.Hosting/AgentSessionStore.cs

Lines 39 to 45 in b2e7706

	/// A task that represents the asynchronous retrieval operation.
	/// The task result contains the serialized session state, or <see langword="null"/> if not found.
	/// </returns>
	public abstract ValueTask<AgentSession> GetSessionAsync(
	AIAgent agent,
	string conversationId,
	CancellationToken cancellationToken = default);

Judging by 1) existing implementations (noop session store, in memory session store), 2) use by AIHostAgent, 3) and the nullability contract, the description should say that a new session must be returned if not found, and that null should not be returned.