Address bug when agent rawrepresentation is a MEAI type and returns it with null RawRep (#1054)

dotnet/samples/GettingStarted/AgentOpenTelemetry/Program.cs

@@ -85,7 +85,7 @@ Console.WriteLine("""
     """);
 
 var endpoint = Environment.GetEnvironmentVariable("AZURE_OPENAI_ENDPOINT") ?? throw new InvalidOperationException("AZURE_OPENAI_ENDPOINT environment variable is not set.");
-var deploymentName = Environment.GetEnvironmentVariable("AZURE_OPENAI_DEPLOYMENT_NAME") ?? "gpt-4o-mini";
+var deploymentName = System.Environment.GetEnvironmentVariable("AZURE_OPENAI_DEPLOYMENT_NAME") ?? "gpt-4o-mini";
 
 // Log application startup
 appLogger.LogInformation("OpenTelemetry Aspire Demo application started");

dotnet/src/Microsoft.Agents.AI/OpenTelemetryAgent.cs

@@ -85,7 +85,7 @@ public sealed class OpenTelemetryAgent : DelegatingAIAgent, IDisposable
 
         var response = await this._otelClient.GetResponseAsync(messages, co, cancellationToken).ConfigureAwait(false);
 
-        return (AgentRunResponse)response.RawRepresentation!;
+        return response.RawRepresentation as AgentRunResponse ?? new AgentRunResponse(response);
     }
 
     /// <inheritdoc/>
@@ -96,7 +96,7 @@ public sealed class OpenTelemetryAgent : DelegatingAIAgent, IDisposable
 
         await foreach (var update in this._otelClient.GetStreamingResponseAsync(messages, co, cancellationToken).ConfigureAwait(false))
         {
-            yield return (AgentRunResponseUpdate)update.RawRepresentation!;
+            yield return update.RawRepresentation as AgentRunResponseUpdate ?? new AgentRunResponseUpdate(update);
         }
     }
 

dotnet/src/Shared/Demos/SampleEnvironment.cs

@@ -7,6 +7,7 @@ using System.Collections;
 using SystemEnvironment = System.Environment;
 
 namespace SampleHelpers;
+
 internal static class SampleEnvironment
 {
     public static string? GetEnvironmentVariable(string key)