Issue with multipart/form-data post and json.net deserializtion (using interfaces)

We use the aspnetcore 2.

We have configured JsonOptions in startup like this.
```csharp
services.AddMvc().AddJsonOptions(options =>
{
options.SerializerSettings.ContractResolver = new DefaultContractResolver();
options.SerializerSettings.Converters = new List {
new JsonDocumentConverter(),
new JsonDocumentMetaConverter(),
//new Bll.FileRecords.JsonDocumentMetaListConverter(),
};
});

public class JsonDocumentConverter : CustomCreationConverter
{
public override IDocument Create(Type objectType)
{
return new LocalDocument();
}
}
public class JsonDocumentMetaConverter : CustomCreationConverter
{
public override IDocumentMeta Create(Type objectType)
{
return new LocalDocumentMeta();
}
}
```

In our controller we have 2 methods
1. The first one is called PostUrlencoded in which we make a http post request with content-type : application/x-www-form-urlencoded.
```csharp
[HttpPost("PostUrlencoded")]
public async Task PostUrlencoded([FromBody]IDocument document)
{ /*...*/ }
```
2.. The second one is called PostΜultipart in which we make a http post request with content-type : multipart/form-data.
```csharp
[HttpPost("PostΜultipart")]
public async Task PostΜultipart([FromForm]IDocument document)
{ /*...*/ }
```

The first method works fine, and the deserialization works fine. In the second method deserialization fails.
The error is:
`Model bound complex types must not be abstract or value types and must have a parameterless constructor.`

That's because the JsonOptions isn't applied.

When we remove the jsonOptions from the startup.cs, we get the same error in both cases.