[DEVEX-222] Ensured that metadata is serialized with auto-serialization as regular system metadata

Author: oskardudycz

Diff for: src/KurrentDB.Client/Core/OperationOptions.cs

@@ -31,6 +31,8 @@ public record OperationOptions {
 	public OperationOptions With(KurrentDBClientOperationOptions clientOperationOptions) =>
 		new() {
 			ThrowOnAppendFailure = ThrowOnAppendFailure ?? clientOperationOptions.ThrowOnAppendFailure,
-			BatchAppendSize      = BatchAppendSize ?? clientOperationOptions.BatchAppendSize
+			BatchAppendSize      = BatchAppendSize ?? clientOperationOptions.BatchAppendSize,
+			Deadline             = Deadline,
+			UserCredentials      = UserCredentials,
 		};
 }

Diff for: src/KurrentDB.Client/Core/Serialization/MessageSerializer.cs

@@ -54,8 +54,10 @@ public static IMessageSerializer With(
 }
 
 class MessageSerializer(SchemaRegistry schemaRegistry) : IMessageSerializer {
-	readonly ISerializer _jsonSerializer =
-		schemaRegistry.GetSerializer(ContentType.Json);
+	readonly SystemTextJsonSerializer _metadataSerializer =
+		new SystemTextJsonSerializer(
+			new SystemTextJsonSerializationSettings { Options = KurrentDBClient.StreamMetadataJsonSerializerOptions }
+		);
 
 	readonly IMessageTypeNamingStrategy _messageTypeNamingStrategy =
 		schemaRegistry.MessageTypeNamingStrategy;
@@ -74,7 +76,7 @@ public EventData Serialize(Message message, MessageSerializationContext serializ
 			.Serialize(data);
 
 		var serializedMetadata = metadata != null
-			? _jsonSerializer.Serialize(metadata)
+			? _metadataSerializer.Serialize(metadata)
 			: ReadOnlyMemory<byte>.Empty;
 
 		return new EventData(
@@ -106,8 +108,8 @@ public bool TryDeserialize(EventRecord record, [NotNullWhen(true)] out Message?
 		}
 
 		object? metadata = record.Metadata.Length > 0 && TryResolveClrMetadataType(record, out var clrMetadataType)
-				? _jsonSerializer.Deserialize(record.Metadata, clrMetadataType!)
-				: null;
+			? _metadataSerializer.Deserialize(record.Metadata, clrMetadataType!)
+			: null;
 
 		deserialized = Message.From(data, metadata, record.EventId);
 		return true;

Diff for: src/KurrentDB.Client/Streams/KurrentDBClient.cs

@@ -13,7 +13,7 @@ namespace KurrentDB.Client {
 	/// The client used for operations on streams.
 	/// </summary>
 	public sealed partial class KurrentDBClient : KurrentDBClientBase {
-		static readonly JsonSerializerOptions StreamMetadataJsonSerializerOptions = new() {
+		internal static readonly JsonSerializerOptions StreamMetadataJsonSerializerOptions = new() {
 			Converters = {
 				StreamMetadataJsonConverter.Instance
 			},