.Net - Agents IReadonlyList instead of IEnumerable (Step #ANY) (micro…

…soft#5832)

### Motivation and Context

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`IEnumerable` can be cumbersome if not required. Identified a usage that
is improved by `IReadOnlyList` (as the usage of `IEnumerable` was
extraneous.)

### Description

<!-- Describe your changes, the overall approach, the underlying design.
These notes will help understanding how your code works. Thanks! -->

Been on the look-out for tuning these signatures...this one slipped
through.

### Contribution Checklist

<!-- Before submitting this PR, please make sure: -->

- [X] The code builds clean without any errors or warnings
- [X] The PR follows the [SK Contribution
Guidelines](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
script](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md#development-scripts)
raises no violations
- [X] All unit tests pass, and I have added new tests where possible
- [X] I didn't break anyone 😄

dotnet/src/Agents/Abstractions/AgentChannel.cs

@@ -16,7 +16,7 @@ public abstract class AgentChannel
     /// </summary>
     /// <param name="history">The chat history at the point the channel is created.</param>
     /// <param name="cancellationToken">The <see cref="CancellationToken"/> to monitor for cancellation requests. The default is <see cref="CancellationToken.None"/>.</param>
-    protected internal abstract Task ReceiveAsync(IEnumerable<ChatMessageContent> history, CancellationToken cancellationToken = default);
+    protected internal abstract Task ReceiveAsync(IReadOnlyList<ChatMessageContent> history, CancellationToken cancellationToken = default);
 
     /// <summary>
     /// Perform a discrete incremental interaction between a single <see cref="Agent"/> and <see cref="AgentChat"/>.

dotnet/src/Agents/Abstractions/ChatHistoryChannel.cs

@@ -34,7 +34,7 @@ protected internal sealed override async IAsyncEnumerable<ChatMessageContent> In
     }
 
     /// <inheritdoc/>
-    protected internal sealed override Task ReceiveAsync(IEnumerable<ChatMessageContent> history, CancellationToken cancellationToken)
+    protected internal sealed override Task ReceiveAsync(IReadOnlyList<ChatMessageContent> history, CancellationToken cancellationToken)
     {
         this._history.AddRange(history);
 

dotnet/src/Agents/Abstractions/Internal/BroadcastQueue.cs

@@ -9,7 +9,7 @@ namespace Microsoft.SemanticKernel.Agents.Internal;
 /// <summary>
 /// Utility class used by <see cref="AgentChat"/> to manage the broadcast of
 /// conversation messages via the <see cref="AgentChannel"/>.
-/// (<see cref="AgentChannel.ReceiveAsync(IEnumerable{ChatMessageContent}, System.Threading.CancellationToken)"/>.)
+/// (<see cref="AgentChannel.ReceiveAsync"/>.)
 /// </summary>
 /// <remarks>
 /// Maintains a set of channel specific queues, each with individual locks, in addition to a global state lock.

dotnet/src/Agents/UnitTests/AgentChannelTests.cs

@@ -57,7 +57,7 @@ protected internal override IAsyncEnumerable<ChatMessageContent> GetHistoryAsync
             throw new NotImplementedException();
         }
 
-        protected internal override Task ReceiveAsync(IEnumerable<ChatMessageContent> history, CancellationToken cancellationToken = default)
+        protected internal override Task ReceiveAsync(IReadOnlyList<ChatMessageContent> history, CancellationToken cancellationToken = default)
         {
             throw new NotImplementedException();
         }

dotnet/src/Agents/UnitTests/Internal/BroadcastQueueTests.cs

@@ -141,7 +141,7 @@ protected internal override IAsyncEnumerable<ChatMessageContent> InvokeAsync(Age
             throw new NotImplementedException();
         }
 
-        protected internal override async Task ReceiveAsync(IEnumerable<ChatMessageContent> history, CancellationToken cancellationToken = default)
+        protected internal override async Task ReceiveAsync(IReadOnlyList<ChatMessageContent> history, CancellationToken cancellationToken = default)
         {
             this.ReceivedMessages.AddRange(history);
             this.ReceiveCount += 1;
@@ -164,7 +164,7 @@ protected internal override IAsyncEnumerable<ChatMessageContent> InvokeAsync(Age
             throw new NotImplementedException();
         }
 
-        protected internal override async Task ReceiveAsync(IEnumerable<ChatMessageContent> history, CancellationToken cancellationToken = default)
+        protected internal override async Task ReceiveAsync(IReadOnlyList<ChatMessageContent> history, CancellationToken cancellationToken = default)
         {
             await Task.Delay(this.ReceiveDuration, cancellationToken);