solving for some CA/Roslynator suggestions

Author: brandonh-msft

src/A2A/Client/A2AClient.cs

@@ -135,7 +135,7 @@ private async IAsyncEnumerable<SseItem<TOutput>> SendRpcSseRequestAsync<TInput,
             "text/event-stream",
             cancellationToken).ConfigureAwait(false);
 
-        var sseParser = SseParser.Create(responseStream, (eventType, data) =>
+        var sseParser = SseParser.Create(responseStream, (_, data) =>
         {
             var reader = new Utf8JsonReader(data);
 
@@ -146,7 +146,12 @@ private async IAsyncEnumerable<SseItem<TOutput>> SendRpcSseRequestAsync<TInput,
                 throw new A2AException(error.Message, (A2AErrorCode)error.Code);
             }
 
-            return JsonSerializer.Deserialize(responseObject?.Result, outputTypeInfo) ??
+            if (responseObject?.Result is null)
+            {
+                throw new InvalidOperationException("Failed to deserialize the event: Result is null.");
+            }
+
+            return responseObject.Result.Deserialize(outputTypeInfo) ??
                 throw new InvalidOperationException("Failed to deserialize the event.");
         });
 

src/A2A/Models/A2AResponse.cs

@@ -10,16 +10,12 @@ namespace A2A;
 [JsonDerivedType(typeof(TaskArtifactUpdateEvent), "artifact-update")]
 [JsonDerivedType(typeof(Message), "message")]
 [JsonDerivedType(typeof(AgentTask), "task")]
-public abstract class A2AEvent
-{
-}
+public abstract class A2AEvent;
 
 /// <summary>
 /// A2A response objects.
 /// </summary>
 [JsonPolymorphic(TypeDiscriminatorPropertyName = "kind")]
 [JsonDerivedType(typeof(Message), "message")]
 [JsonDerivedType(typeof(AgentTask), "task")]
-public abstract class A2AResponse : A2AEvent
-{
-}
+public abstract class A2AResponse : A2AEvent;