Add polymorphic support to SignalR STJ

[BrennanConroy]

Fixes #52342

@eiriktsarpalis is there any downside(s)/gotchas to calling JsonSerializer.Serialize without the actual type of the object?

void Write(object obj)
{
    JsonSerializer.Serialize(obj, obj.GetType(), options);
    // vs.
    JsonSerializer.Serialize(obj, options);
}

[eiriktsarpalis]

is there any downside(s)/gotchas to calling JsonSerializer.Serialize without the actual type of the object?

Not really, if anything the overload without the Type argument should be faster in certain cases since it caches the most recently used type medata.

[BrennanConroy]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 3 pipeline(s).

[davidfowl]

For AOT, we'll need to pass in the type info AFAIK,.

[TonEnfer]

Hello @BrennanConroy
Can we expect a fix for this in NET 8?

[ghost]

Hi @TonEnfer. It looks like you just commented on a closed PR. The team will most probably miss it. If you'd like to bring something important up to their attention, consider filing a new issue and add enough details to build context.

[BrennanConroy]

Unlikely, this is feature work, not fixing a regression or a security concern.
https://github.com/dotnet/aspnetcore/blob/main/docs/Servicing.md#servicing-bar