JsonSerializerSettings not honored for Field Expressions

[octocat-mona]

NEST/Elasticsearch.Net version:
7.0.1

NEST.JsonNetSerializer version:
7.0.1

Elasticsearch version:
7.2.0

Description of the problem including expected versus actual behavior:
Expected: be able to query on a field using an Expression lambda which should honor the [JsonProperty] attributes when configured using JsonSerializerSettings just like in NEST 6.8.0.

Actual: No query results are returned.

Steps to reproduce:

1. DELETE my-index
2. Index a document and query it using a date range filter:

var pool = new SingleNodeConnectionPool(new Uri("https://localhost.fiddler:9200"));
var settings = new ConnectionSettings(pool, (serializer, connectionSettings)
        => new JsonNetSerializer(serializer, connectionSettings))
    .BasicAuthentication("elastic", "elastic");
var client = new ElasticClient(settings);
var doc = new DocumentModel { Timestamp = DateTime.UtcNow, DocumentName = "Doc 1" };

await client.IndexAsync(doc, descriptor => descriptor
    .Index("my-index")
    .Refresh(Refresh.True)
);

var countResponse = await client.CountAsync<DocumentModel>(descriptor => descriptor
    .Index("my-index")
);
long totalDocs = countResponse.Count; // totalDocs = 1

var searchResponse = await client.SearchAsync<DocumentModel>(descriptor => descriptor
    .Index("my-index")
    .Query(q => q
        .DateRange(range => range
            .Field(model => model.Timestamp)
            .GreaterThan("1970-01-01"))
    )
);
int count = searchResponse.Documents.Count; // count = 0

The poco model:

public class DocumentModel
{
    [JsonProperty("@timestamp")]
    public DateTime Timestamp { get; set; }

    [JsonProperty("document_name")]
    public string DocumentName { get; set; }
}

3. Notice that the date range filter uses the lowercased Timestamp property name, not @timestamp from the [JsonProperty] attribute:

POST https://localhost:9200/my-index/_search?typed_keys=true HTTP/1.1
Accept: application/json
Content-Type: application/json
User-Agent: elasticsearch-net/7.0.1 (Microsoft Windows 10.0.17134; .NET Framework 4.7.3416.0; Nest)
Authorization: Basic ZWxhc3RpYzplbGFzdGlj
Host: localhost:9200
Content-Length: 53

{"query":{"range":{"timestamp":{"gt":"1970-01-01"}}}}

[octocat-mona]

Also the documentation for 7.x seems not updated yet?
It still mentions Newtonsoft Json which is removed completely now?

[russcam]

@KPStolk You are correct that some of the documentation needs to be updated to reflect that 7.x no longer ships with an internalized version of Json.NET. The use of NEST.JsonNetSerializer nuget package is still valid however.

[russcam]

Opened #3942 to address