[Core] Update RequestFailedException to use source generation for serialization

sdk/core/Azure.Core/src/RequestFailedException.cs

@@ -259,8 +259,14 @@ internal static bool TryExtractErrorContent(Response response, out ResponseError
                     return false;
                 }
                 // Try the ErrorResponse format and fallback to the ResponseError format.
+
+#if NET6_0_OR_GREATER
+                error = System.Text.Json.JsonSerializer.Deserialize<ErrorResponse>(content, ResponseErrorSourceGenerationContext.Default.ErrorResponse)?.Error;
+                error ??= System.Text.Json.JsonSerializer.Deserialize<ResponseError>(content, ResponseErrorSourceGenerationContext.Default.ResponseError);
+#else
                 error = System.Text.Json.JsonSerializer.Deserialize<ErrorResponse>(content)?.Error;
                 error ??= System.Text.Json.JsonSerializer.Deserialize<ResponseError>(content);
+#endif
             }
             catch (Exception)
             {
@@ -271,7 +277,8 @@ internal static bool TryExtractErrorContent(Response response, out ResponseError
             return error != null;
         }
 
-        private class ErrorResponse
+        // This class needs to be internal rather than private so that it can be used by the System.Text.Json source generator
+        internal class ErrorResponse
         {
             [System.Text.Json.Serialization.JsonPropertyName("error")]
             public ResponseError? Error { get; set; }

sdk/core/Azure.Core/src/ResponseError.cs

@@ -75,7 +75,8 @@ internal ResponseError(string? code, string? message, string? target, JsonElemen
         /// </summary>
         internal IReadOnlyList<ResponseError> Details { get; }
 
-        private class Converter : JsonConverter<ResponseError?>
+        // This class needs to be internal rather than private so that it can be used by the System.Text.Json source generator
+        internal class Converter : JsonConverter<ResponseError?>
         {
             public override ResponseError? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
             {

sdk/core/Azure.Core/src/ResponseErrorSourceGenerationContext.cs

@@ -0,0 +1,27 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using Azure.Core;
+
+namespace Azure
+{
+#if NET6_0_OR_GREATER
+    [JsonSerializable(typeof(ResponseError))]
+    [JsonSerializable(typeof(RequestFailedException.ErrorResponse))]
+    [JsonSerializable(typeof(ResponseInnerError))]
+    [JsonSerializable(typeof(JsonElement))]
+    [JsonSerializable(typeof(JsonDocument))]
+    [JsonSerializable(typeof(JsonValueKind))]
+    [JsonSerializable(typeof(string))]
+    [JsonSerializable(typeof(bool))]
+    [JsonSerializable(typeof(List<ResponseError>))]
+    internal partial class ResponseErrorSourceGenerationContext : JsonSerializerContext
+    {
+    }
+#endif
+}