PropertyNamingPolicy null walue

[amoraller]

I think, we should support unsetted value for JsonRpcServerOptions.DefaultDataJsonSerializerOptions.PropertyNamingPolicy

Today, i use this policy

class UnsetNamingPolicy : JsonNamingPolicy
{
    public override string ConvertName(string name) => name;
}

For example System.Text.Json support null value for policy
https://github.com/dotnet/corefx/blob/e667c29636a622eb4f9493f75232b44e0ae90b29/src/System.Text.Json/src/System/Text/Json/Serialization/JsonPropertyInfo.cs#L106-L119

[OptimumDev]

Hello! Thank you for the issue.
You are right, null PropertyNamingPolicy should be supported and we tried to achive it, but looks like we missed couple of spots.
We will fix it when we will able to, or you can contribute by PR 😉