FiltersAggregation doesn't work due to missing JsonConverter implementation

[rustunooldu]

Elastic.Clients.Elasticsearch version: 8.1.0

Elasticsearch version: 8.7.0

.NET runtime version: .NET 6.0

Operating system version: Win 11

Description of the problem including expected versus actual behavior:
I'm trying to create a NestedAggregation with FiltersAggregation sub-aggregation (corresponding syntax can be found here).

FiltersAggregation.Filters property is of type Buckets<Query>?, which is mapped to BucketsConverter in UnionConverted.cs which throws a not implemented exception during serialization.

Steps to reproduce:
Try creating any search request that utilizes FiltersAggregation.

var request = new SearchRequest<Product>();
request.Aggregations = new NestedAggregation("product_attributes")
{
	Path = "primaryAttributes",
	Aggregations = new FiltersAggregation("name_filter")
	{
		Filters = new Buckets<Query>(
			new List<Query>
			{
				new TermQuery("primaryAttributes.name")
				{
					Value = "Color"
				}
			}),
		Aggregations = new TermsAggregation("color_terms")
		{
			Field = "primaryAttributes.value"
		}
	}
};
var response = await _client.SearchAsync<Product>(request);

Provide DebugInformation (if relevant):

Stack Trace

# FailureReason: Unrecoverable/Unexpected BadRequest while attempting POST on https://localhost:9200/dev_product_v1/_search?error_trace=true&typed_keys=true
 - [1] BadRequest: Node: https://localhost:9200/ Exception: NotImplementedException Took: 00:00:00.0149547
# Audit exception in step 1 BadRequest:
System.NotImplementedException: The method or operation is not implemented.
   at Elastic.Clients.Elasticsearch.Serialization.UnionConverter.BucketsConverter`1.Write(Utf8JsonWriter writer, Buckets`1 value, JsonSerializerOptions options) in /_/src/Elastic.Clients.Elasticsearch/Serialization/UnionConverter.cs:line 226
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteUsingSerializer[TValue](Utf8JsonWriter writer, TValue& value, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Serialize[TValue](Utf8JsonWriter writer, TValue value, JsonSerializerOptions options)
   at Elastic.Clients.Elasticsearch.Aggregations.FiltersAggregationConverter.Write(Utf8JsonWriter writer, FiltersAggregation value, JsonSerializerOptions options) in /_/src/Elastic.Clients.Elasticsearch/_Generated/Types/Aggregations/FiltersAggregation.g.cs:line 121
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCoreAsObject(Utf8JsonWriter writer, Object value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteUsingSerializer[TValue](Utf8JsonWriter writer, TValue& value, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Serialize(Utf8JsonWriter writer, Object value, Type inputType, JsonSerializerOptions options)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.Converters.DictionaryOfTKeyTValueConverter`3.OnWriteResume(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonDictionaryConverter`3.OnTryWrite(Utf8JsonWriter writer, TDictionary dictionary, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteUsingSerializer[TValue](Utf8JsonWriter writer, TValue& value, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Serialize[TValue](Utf8JsonWriter writer, TValue value, JsonSerializerOptions options)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteUsingSerializer[TValue](Utf8JsonWriter writer, TValue& value, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Serialize[TValue](Utf8JsonWriter writer, TValue value, JsonSerializerOptions options)
   at Elastic.Clients.Elasticsearch.Aggregations.NestedAggregationConverter.Write(Utf8JsonWriter writer, NestedAggregation value, JsonSerializerOptions options) in /_/src/Elastic.Clients.Elasticsearch/_Generated/Types/Aggregations/NestedAggregation.g.cs:line 110
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCoreAsObject(Utf8JsonWriter writer, Object value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteUsingSerializer[TValue](Utf8JsonWriter writer, TValue& value, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Serialize(Utf8JsonWriter writer, Object value, Type inputType, JsonSerializerOptions options)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.Converters.DictionaryOfTKeyTValueConverter`3.OnWriteResume(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonDictionaryConverter`3.OnTryWrite(Utf8JsonWriter writer, TDictionary dictionary, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteUsingSerializer[TValue](Utf8JsonWriter writer, TValue& value, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Serialize[TValue](Utf8JsonWriter writer, TValue value, JsonSerializerOptions options)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteUsingSerializer[TValue](Utf8JsonWriter writer, TValue& value, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Serialize[TValue](Utf8JsonWriter writer, TValue value, JsonSerializerOptions options)
   at Elastic.Clients.Elasticsearch.SearchRequestConverter.Write(Utf8JsonWriter writer, SearchRequest value, JsonSerializerOptions options) in /_/src/Elastic.Clients.Elasticsearch/_Generated/Api/SearchRequest.g.cs:line 394
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteCore[TValue](JsonConverter jsonConverter, Utf8JsonWriter writer, TValue& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteStreamAsync[TValue](Stream utf8Json, TValue value, JsonTypeInfo jsonTypeInfo, CancellationToken cancellationToken)
   at System.Text.Json.JsonSerializer.WriteStreamAsync[TValue](Stream utf8Json, TValue value, JsonTypeInfo jsonTypeInfo, CancellationToken cancellationToken)
   at System.Text.Json.JsonSerializer.WriteStreamAsync[TValue](Stream utf8Json, TValue value, JsonTypeInfo jsonTypeInfo, CancellationToken cancellationToken)
   at Elastic.Transport.PostData.SerializableData`1.WriteAsync(Stream writableStream, ITransportConfiguration settings, CancellationToken cancellationToken)
   at Elastic.Transport.HttpTransportClient.SetContentAsync(HttpRequestMessage message, RequestData requestData, CancellationToken cancellationToken)
   at Elastic.Transport.HttpTransportClient.RequestAsync[TResponse](RequestData requestData, CancellationToken cancellationToken)
   at Elastic.Transport.DefaultRequestPipeline`1.CallProductEndpointAsync[TResponse](RequestData requestData, CancellationToken cancellationToken)
   at Elastic.Transport.DefaultHttpTransport`1.RequestAsync[TResponse](HttpMethod method, String path, PostData data, RequestParameters requestParameters, CancellationToken cancellationToken)
# Inner Exception: The method or operation is not implemented.
System.NotImplementedException: The method or operation is not implemented.
   at Elastic.Clients.Elasticsearch.Serialization.UnionConverter.BucketsConverter`1.Write(Utf8JsonWriter writer, Buckets`1 value, JsonSerializerOptions options) in /_/src/Elastic.Clients.Elasticsearch/Serialization/UnionConverter.cs:line 226
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteUsingSerializer[TValue](Utf8JsonWriter writer, TValue& value, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Serialize[TValue](Utf8JsonWriter writer, TValue value, JsonSerializerOptions options)
   at Elastic.Clients.Elasticsearch.Aggregations.FiltersAggregationConverter.Write(Utf8JsonWriter writer, FiltersAggregation value, JsonSerializerOptions options) in /_/src/Elastic.Clients.Elasticsearch/_Generated/Types/Aggregations/FiltersAggregation.g.cs:line 121
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCoreAsObject(Utf8JsonWriter writer, Object value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteUsingSerializer[TValue](Utf8JsonWriter writer, TValue& value, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Serialize(Utf8JsonWriter writer, Object value, Type inputType, JsonSerializerOptions options)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.Converters.DictionaryOfTKeyTValueConverter`3.OnWriteResume(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonDictionaryConverter`3.OnTryWrite(Utf8JsonWriter writer, TDictionary dictionary, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteUsingSerializer[TValue](Utf8JsonWriter writer, TValue& value, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Serialize[TValue](Utf8JsonWriter writer, TValue value, JsonSerializerOptions options)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteUsingSerializer[TValue](Utf8JsonWriter writer, TValue& value, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Serialize[TValue](Utf8JsonWriter writer, TValue value, JsonSerializerOptions options)
   at Elastic.Clients.Elasticsearch.Aggregations.NestedAggregationConverter.Write(Utf8JsonWriter writer, NestedAggregation value, JsonSerializerOptions options) in /_/src/Elastic.Clients.Elasticsearch/_Generated/Types/Aggregations/NestedAggregation.g.cs:line 110
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCoreAsObject(Utf8JsonWriter writer, Object value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteUsingSerializer[TValue](Utf8JsonWriter writer, TValue& value, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Serialize(Utf8JsonWriter writer, Object value, Type inputType, JsonSerializerOptions options)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.Converters.DictionaryOfTKeyTValueConverter`3.OnWriteResume(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonDictionaryConverter`3.OnTryWrite(Utf8JsonWriter writer, TDictionary dictionary, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteUsingSerializer[TValue](Utf8JsonWriter writer, TValue& value, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Serialize[TValue](Utf8JsonWriter writer, TValue value, JsonSerializerOptions options)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteUsingSerializer[TValue](Utf8JsonWriter writer, TValue& value, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Serialize[TValue](Utf8JsonWriter writer, TValue value, JsonSerializerOptions options)
   at Elastic.Clients.Elasticsearch.SearchRequestConverter.Write(Utf8JsonWriter writer, SearchRequest value, JsonSerializerOptions options) in /_/src/Elastic.Clients.Elasticsearch/_Generated/Api/SearchRequest.g.cs:line 394
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteCore[TValue](JsonConverter jsonConverter, Utf8JsonWriter writer, TValue& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteStreamAsync[TValue](Stream utf8Json, TValue value, JsonTypeInfo jsonTypeInfo, CancellationToken cancellationToken)
   at System.Text.Json.JsonSerializer.WriteStreamAsync[TValue](Stream utf8Json, TValue value, JsonTypeInfo jsonTypeInfo, CancellationToken cancellationToken)
   at System.Text.Json.JsonSerializer.WriteStreamAsync[TValue](Stream utf8Json, TValue value, JsonTypeInfo jsonTypeInfo, CancellationToken cancellationToken)
   at Elastic.Transport.PostData.SerializableData`1.WriteAsync(Stream writableStream, ITransportConfiguration settings, CancellationToken cancellationToken)
   at Elastic.Transport.HttpTransportClient.SetContentAsync(HttpRequestMessage message, RequestData requestData, CancellationToken cancellationToken)
   at Elastic.Transport.HttpTransportClient.RequestAsync[TResponse](RequestData requestData, CancellationToken cancellationToken)
   at Elastic.Transport.DefaultRequestPipeline`1.CallProductEndpointAsync[TResponse](RequestData requestData, CancellationToken cancellationToken)
   at Elastic.Transport.DefaultHttpTransport`1.RequestAsync[TResponse](HttpMethod method, String path, PostData data, RequestParameters requestParameters, CancellationToken cancellationToken)
# Exception:
Elastic.Transport.UnexpectedTransportException: The method or operation is not implemented.
 ---> System.NotImplementedException: The method or operation is not implemented.
   at Elastic.Clients.Elasticsearch.Serialization.UnionConverter.BucketsConverter`1.Write(Utf8JsonWriter writer, Buckets`1 value, JsonSerializerOptions options) in /_/src/Elastic.Clients.Elasticsearch/Serialization/UnionConverter.cs:line 226
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteUsingSerializer[TValue](Utf8JsonWriter writer, TValue& value, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Serialize[TValue](Utf8JsonWriter writer, TValue value, JsonSerializerOptions options)
   at Elastic.Clients.Elasticsearch.Aggregations.FiltersAggregationConverter.Write(Utf8JsonWriter writer, FiltersAggregation value, JsonSerializerOptions options) in /_/src/Elastic.Clients.Elasticsearch/_Generated/Types/Aggregations/FiltersAggregation.g.cs:line 121
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCoreAsObject(Utf8JsonWriter writer, Object value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteUsingSerializer[TValue](Utf8JsonWriter writer, TValue& value, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Serialize(Utf8JsonWriter writer, Object value, Type inputType, JsonSerializerOptions options)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.Converters.DictionaryOfTKeyTValueConverter`3.OnWriteResume(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonDictionaryConverter`3.OnTryWrite(Utf8JsonWriter writer, TDictionary dictionary, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteUsingSerializer[TValue](Utf8JsonWriter writer, TValue& value, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Serialize[TValue](Utf8JsonWriter writer, TValue value, JsonSerializerOptions options)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteUsingSerializer[TValue](Utf8JsonWriter writer, TValue& value, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Serialize[TValue](Utf8JsonWriter writer, TValue value, JsonSerializerOptions options)
   at Elastic.Clients.Elasticsearch.Aggregations.NestedAggregationConverter.Write(Utf8JsonWriter writer, NestedAggregation value, JsonSerializerOptions options) in /_/src/Elastic.Clients.Elasticsearch/_Generated/Types/Aggregations/NestedAggregation.g.cs:line 110
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCoreAsObject(Utf8JsonWriter writer, Object value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteUsingSerializer[TValue](Utf8JsonWriter writer, TValue& value, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Serialize(Utf8JsonWriter writer, Object value, Type inputType, JsonSerializerOptions options)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.Converters.DictionaryOfTKeyTValueConverter`3.OnWriteResume(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonDictionaryConverter`3.OnTryWrite(Utf8JsonWriter writer, TDictionary dictionary, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteUsingSerializer[TValue](Utf8JsonWriter writer, TValue& value, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Serialize[TValue](Utf8JsonWriter writer, TValue value, JsonSerializerOptions options)
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteUsingSerializer[TValue](Utf8JsonWriter writer, TValue& value, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Serialize[TValue](Utf8JsonWriter writer, TValue value, JsonSerializerOptions options)
   at Elastic.Clients.Elasticsearch.SearchRequestConverter.Write(Utf8JsonWriter writer, SearchRequest value, JsonSerializerOptions options) in /_/src/Elastic.Clients.Elasticsearch/_Generated/Api/SearchRequest.g.cs:line 394
   at System.Text.Json.Serialization.JsonConverter`1.TryWrite(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.Serialization.JsonConverter`1.WriteCore(Utf8JsonWriter writer, T& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteCore[TValue](JsonConverter jsonConverter, Utf8JsonWriter writer, TValue& value, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteStreamAsync[TValue](Stream utf8Json, TValue value, JsonTypeInfo jsonTypeInfo, CancellationToken cancellationToken)
   at System.Text.Json.JsonSerializer.WriteStreamAsync[TValue](Stream utf8Json, TValue value, JsonTypeInfo jsonTypeInfo, CancellationToken cancellationToken)
   at System.Text.Json.JsonSerializer.WriteStreamAsync[TValue](Stream utf8Json, TValue value, JsonTypeInfo jsonTypeInfo, CancellationToken cancellationToken)
   at Elastic.Transport.PostData.SerializableData`1.WriteAsync(Stream writableStream, ITransportConfiguration settings, CancellationToken cancellationToken)
   at Elastic.Transport.HttpTransportClient.SetContentAsync(HttpRequestMessage message, RequestData requestData, CancellationToken cancellationToken)
   at Elastic.Transport.HttpTransportClient.RequestAsync[TResponse](RequestData requestData, CancellationToken cancellationToken)
   at Elastic.Transport.DefaultRequestPipeline`1.CallProductEndpointAsync[TResponse](RequestData requestData, CancellationToken cancellationToken)
   at Elastic.Transport.DefaultHttpTransport`1.RequestAsync[TResponse](HttpMethod method, String path, PostData data, RequestParameters requestParameters, CancellationToken cancellationToken)
   --- End of inner exception stack trace ---
   at Elastic.Transport.DefaultHttpTransport`1.ThrowUnexpectedTransportException[TResponse](Exception killerException, List`1 seenExceptions, RequestData requestData, TResponse response, RequestPipeline pipeline)
   at Elastic.Transport.DefaultHttpTransport`1.RequestAsync[TResponse](HttpMethod method, String path, PostData data, RequestParameters requestParameters, CancellationToken cancellationToken)

[rustunooldu]

On an unrelated note, are there any plans to support FilterAggregation (single bucket version) in future releases? That functionality is currently missing in 8.x

[stevejgordon]

Thanks for reporting this, @rustunooldu. We'll take a look at fixing this. As for FilterAggregation - yes, we plan to reintroduce all previously supported aggregations. I can't recall the exact reason we didn't generate this one, but we can take a look in a future release.