#2183 strikes again, causing a null reference when JsonNetSerializer() was being injected, because we use a custom ConnectionSettingsAwareSerializerBase implementation in our tests this was not caught. Also this PR renames our internal json converter from JsonNetSerializer to InternalSerializer, otherwise you would get a confusing error message about using an internal type before actually referencing Nest.JsonNetSerializer

Author: Mpdreamz

src/Nest/CommonAbstractions/ConnectionSettings/ConnectionSettingsBase.cs

@@ -89,7 +89,7 @@ IPropertyMappingProvider propertyMappingProvider
 		)
 			: base(connectionPool, connection, null)
 		{
-			var defaultSerializer = new JsonNetSerializer(this);
+			var defaultSerializer = new InternalSerializer(this);
 			this._sourceSerializer = sourceSerializerFactory?.Invoke(defaultSerializer, this) ?? defaultSerializer;
 			this.UseThisRequestResponseSerializer = defaultSerializer;
 			this._propertyMappingProvider = propertyMappingProvider ?? new PropertyMappingProvider();

src/Nest/CommonAbstractions/ConnectionSettings/ConnectionSettingsValuesExtensions.cs

@@ -6,7 +6,7 @@ namespace Nest
 {
 	internal static class ConnectionSettingsValuesExtensions
 	{
-		public static JsonNetSerializer CreateStateful(this IConnectionSettingsValues settings, JsonConverter converter)
+		public static InternalSerializer CreateStateful(this IConnectionSettingsValues settings, JsonConverter converter)
 		{
 			var s = (settings as ConnectionSettings)
 				?? throw new NullReferenceException($"Stateful serializer expected {nameof(IConnectionSettingsValues)} to be {nameof(ConnectionSettings)}");

src/Nest/CommonAbstractions/SerializationBehavior/JsonNetSerializer.cs renamed to src/Nest/CommonAbstractions/SerializationBehavior/InternalSerializer.cs

@@ -10,8 +10,8 @@
 namespace Nest
 {
 
-	/// <summary> A JSON serializer that uses Json.NET for serialization </summary>
-	internal class JsonNetSerializer : IElasticsearchSerializer
+	/// <summary>The built in internal serializer that the high level client NEST uses.</summary>
+	internal class InternalSerializer : IElasticsearchSerializer
 	{
 		private static readonly Encoding ExpectedEncoding = new UTF8Encoding(false);
 		private readonly JsonSerializer _defaultSerializer;
@@ -34,12 +34,12 @@ internal class JsonNetSerializer : IElasticsearchSerializer
 		// to be a good compromise buffer size for performance throughput and bytes allocated.
 		protected virtual int BufferSize => 1024;
 
-		public JsonNetSerializer(IConnectionSettingsValues settings) : this(settings, null) { }
+		public InternalSerializer(IConnectionSettingsValues settings) : this(settings, null) { }
 
 		/// <summary>
 		/// this constructor is only here for stateful (de)serialization
 		/// </summary>
-		protected internal JsonNetSerializer(IConnectionSettingsValues settings, JsonConverter statefulConverter)
+		protected internal InternalSerializer(IConnectionSettingsValues settings, JsonConverter statefulConverter)
 		{
 			this.Settings = settings;
 			var piggyBackState = statefulConverter == null ? null : new JsonConverterPiggyBackState { ActualJsonConverter = statefulConverter };

src/Nest/CommonAbstractions/SerializationBehavior/StatefulSerializerFactory.cs

@@ -9,7 +9,7 @@ namespace Nest
 {
 	internal class StatefulSerializerFactory
 	{
-		public JsonNetSerializer CreateStateful(IConnectionSettingsValues settings, JsonConverter converter) =>
-			new JsonNetSerializer(settings, converter);
+		public InternalSerializer CreateStateful(IConnectionSettingsValues settings, JsonConverter converter) =>
+			new InternalSerializer(settings, converter);
 	}
 }

src/Serializers/Nest.JsonNetSerializer/ConnectionSettingsAwareSerializerBase.Customization.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.IO;
 using System.Text;
 using System.Threading;
@@ -61,6 +62,7 @@ public void Serialize<T>(T data, Stream stream, SerializationFormatting formatti
 
 		//we still support net45 so Task.Completed is not available
 		private static readonly Task CompletedTask = Task.FromResult(false);
+
 		public Task SerializeAsync<T>(T data, Stream stream, SerializationFormatting formatting = SerializationFormatting.Indented,
 			CancellationToken cancellationToken = default(CancellationToken))
 		{

src/Serializers/Nest.JsonNetSerializer/ConnectionSettingsAwareSerializerBase.Serializer.cs

@@ -10,15 +10,31 @@ namespace Nest.JsonNetSerializer
 {
 	public abstract partial class ConnectionSettingsAwareSerializerBase
 	{
+		protected Func<JsonSerializerSettings> JsonSerializerSettingsFactory { get; }
+		protected Action<ConnectionSettingsAwareContractResolver> ModifyContractResolverCallback { get; }
+		protected IEnumerable<JsonConverter> ContractJsonConverters { get; }
+
 		protected IConnectionSettingsValues ConnectionSettings { get; }
+
 		protected IElasticsearchSerializer BuiltinSerializer { get; }
 
 		private List<JsonConverter> Converters { get; }
 
-		protected ConnectionSettingsAwareSerializerBase(
+		protected ConnectionSettingsAwareSerializerBase(IElasticsearchSerializer builtinSerializer, IConnectionSettingsValues connectionSettings)
+			: this(builtinSerializer, connectionSettings, null, null, null) { }
+
+		internal ConnectionSettingsAwareSerializerBase(
 			IElasticsearchSerializer builtinSerializer,
-			IConnectionSettingsValues connectionSettings)
+			IConnectionSettingsValues connectionSettings,
+			Func<JsonSerializerSettings> jsonSerializerSettingsFactory,
+			Action<ConnectionSettingsAwareContractResolver> modifyContractResolver,
+			IEnumerable<JsonConverter> contractJsonConverters)
 		{
+
+			JsonSerializerSettingsFactory = jsonSerializerSettingsFactory;
+			ModifyContractResolverCallback = modifyContractResolver;
+			ContractJsonConverters = contractJsonConverters ?? Enumerable.Empty<JsonConverter>();
+
 			ConnectionSettings = connectionSettings;
 			BuiltinSerializer = builtinSerializer;
 			this.Converters = new List<JsonConverter>
@@ -28,62 +44,32 @@ protected ConnectionSettingsAwareSerializerBase(
 			};
 			_serializer = CreateSerializer(SerializationFormatting.Indented);
 			_collapsedSerializer = CreateSerializer(SerializationFormatting.None);
-
 		}
 
+
 		private JsonSerializer CreateSerializer(SerializationFormatting formatting)
 		{
-			var s = CreateJsonSerializerSettings();
+			var s = CreateJsonSerializerSettings() ?? new JsonSerializerSettings();;
 			var converters = CreateJsonConverters() ?? Enumerable.Empty<JsonConverter>();
 			var contract = CreateContractResolver();
 			s.Formatting = formatting == SerializationFormatting.Indented ? Formatting.Indented : Formatting.None;
 			s.ContractResolver = contract;
 			s.Converters = converters.Concat(this.Converters).ToList();
 			return JsonSerializer.Create(s);
 		}
+
 		private IContractResolver CreateContractResolver()
 		{
 			var contract = new ConnectionSettingsAwareContractResolver(this.ConnectionSettings);
 			ModifyContractResolver(contract);
 			return contract;
 		}
 
-		protected abstract JsonSerializerSettings CreateJsonSerializerSettings();
-
-		//TODO
-		protected abstract IEnumerable<JsonConverter> CreateJsonConverters();
-
-		protected virtual void ModifyContractResolver(ConnectionSettingsAwareContractResolver resolver) { }
-	}
-
-	public class JsonNetSerializer : ConnectionSettingsAwareSerializerBase
-	{
-		private readonly Func<JsonSerializerSettings> _jsonSerializerSettingsFactory;
-		private readonly Action<ConnectionSettingsAwareContractResolver> _modifyContractResolver;
-		private readonly IEnumerable<JsonConverter> _contractJsonConverters;
-
-		public static IElasticsearchSerializer Default(IElasticsearchSerializer builtin, IConnectionSettingsValues values)
-			=> new JsonNetSerializer(builtin, values);
-
-		public JsonNetSerializer(
-			IElasticsearchSerializer builtinSerializer,
-			IConnectionSettingsValues connectionSettings,
-			Func<JsonSerializerSettings> jsonSerializerSettingsFactory = null,
-			Action<ConnectionSettingsAwareContractResolver> modifyContractResolver = null,
-			IEnumerable<JsonConverter> contractJsonConverters = null)
-			: base(builtinSerializer, connectionSettings)
-		{
-			_jsonSerializerSettingsFactory = jsonSerializerSettingsFactory;
-			_modifyContractResolver = modifyContractResolver;
-			_contractJsonConverters = contractJsonConverters ?? Enumerable.Empty<JsonConverter>();
-		}
-
-		protected override JsonSerializerSettings CreateJsonSerializerSettings() => _jsonSerializerSettingsFactory?.Invoke();
-
-		protected override IEnumerable<JsonConverter> CreateJsonConverters() => _contractJsonConverters;
+		protected virtual JsonSerializerSettings CreateJsonSerializerSettings() => JsonSerializerSettingsFactory?.Invoke();
 
-		protected override void ModifyContractResolver(ConnectionSettingsAwareContractResolver resolver) =>
-			_modifyContractResolver?.Invoke(resolver);
+		protected virtual IEnumerable<JsonConverter> CreateJsonConverters() => ContractJsonConverters;
 
+		protected virtual void ModifyContractResolver(ConnectionSettingsAwareContractResolver resolver) =>
+			ModifyContractResolverCallback?.Invoke(resolver);
 	}
 }

src/Serializers/Nest.JsonNetSerializer/JsonNetSerializer.cs

@@ -0,0 +1,24 @@
+using System;
+using System.Collections.Generic;
+using Elasticsearch.Net;
+using Newtonsoft.Json;
+
+namespace Nest.JsonNetSerializer
+{
+	public class JsonNetSerializer : ConnectionSettingsAwareSerializerBase
+	{
+		public static IElasticsearchSerializer Default(IElasticsearchSerializer builtin, IConnectionSettingsValues values)
+			=> new JsonNetSerializer(builtin, values);
+
+		public JsonNetSerializer(
+			IElasticsearchSerializer builtinSerializer,
+			IConnectionSettingsValues connectionSettings,
+			Func<JsonSerializerSettings> jsonSerializerSettingsFactory = null,
+			Action<ConnectionSettingsAwareContractResolver> modifyContractResolver = null,
+			IEnumerable<JsonConverter> contractJsonConverters = null)
+			: base(builtinSerializer, connectionSettings, jsonSerializerSettingsFactory, modifyContractResolver, contractJsonConverters)
+		{
+		}
+
+	}
+}

src/Tests/Framework/ManagedElasticsearch/SourceSerializers/TestSourceSerializerBase.cs

@@ -28,7 +28,6 @@ protected override IEnumerable<JsonConverter> CreateJsonConverters()
 		protected override void ModifyContractResolver(ConnectionSettingsAwareContractResolver resolver)
 		{
 			resolver.NamingStrategy = new CamelCaseNamingStrategy();
-			base.ModifyContractResolver(resolver);
 		}
 	}
 }