Support serializing exceptions like Serilog.Sinks.Elasticsearch

[AlexGoris-KasparSolutions]

Potential dupe of #139 , but am still facing the same issue with Serilog on 1.5.3

ECS integration/library project(s) (e.g. Elastic.CommonSchema.Serilog): Elastic.CommonSchema.Serilog

ECS schema version (e.g. 1.4.0): 1.5.3

ECS .NET assembly version (e.g. 1.4.2): 1.5.3

Elasticsearch version (if applicable): 7.13.1

.NET framework / OS: .NET 5.0 / windows 10

Description of the problem, including expected versus actual behavior:
When using ECS with Serilog, exception properties are not sent to ES. I expect to see various exceptions.* properties in my log messages.

Steps to reproduce:
I'm configuring Serilog with the ES sink like so:

var elasticSinkOptions = new ElasticsearchSinkOptions(new Uri(elasticSettings.Uri))
{
    AutoRegisterTemplate = true,
    IndexFormat = $"logs-{indexName}",
    BatchAction = ElasticOpType.Create,
    CustomFormatter = new EcsTextFormatter()
};
Log.Logger = new LoggerConfiguration()
    .ReadFrom.Configuration(configuration)
    .Enrich.FromLogContext()
    .Enrich.WithProperty("Application", "MyService")
    .WriteTo.Elasticsearch(elasticSinkOptions)
    .WriteTo.Console(outputTemplate:
        "[{Timestamp:HH:mm:ss} {Level:u3}] [{SourceContext}] {Message:lj}{NewLine}{Exception}");

When doing e.g.:

try
{
    throw new Exception("Some exception");
}
catch (Exception e)
{
    Log.LogError(e, "Error occurred");
}

The log is sent to ES, but does not include information about the exception, the custom property (.Enrich.WithProperty("Application", "MyService")), does get sent to ES.
When removing CustomFormatter = new EcsTextFormatter() from the ES sink configuration, the exception does get sent to ES (in the exceptions.* properties), but my custom property not anymore.

[AlexGoris-KasparSolutions]

I did some more research since this problem is really starting to annoy us.
1.5.1 does not have this problem, neither does 1.6.1-alpha1.

Any schedule on a non-prerelease of 1.6.1?

[fabianrieder]

I also do still have the same issue as mentioned in #139 . Current Installed version is 1.5.3

[Mpdreamz]

Thanks for reporting this took me a while to parse this is actually a feature request to suppot the exceptions.* property just like Serilog.Sinks.Elasticsearch. A feature I actually contributed there back in '15 🐱

Here's an old gist of that output:

https://gist.github.com/Mpdreamz/9fe1e18aca522f50b702

exceptions.* is not ECS compliant. Today ECS has no notion of serializing stack frames although it did add error.stack_trace since our last release:

elastic/ecs#562