Factory functions that return a generic produce invalid code

I've found this with MediatR when producing a notification handler. A field with this name is created

```csharp
Factor_MediatR_ICancellableAsyncNotificationHandler`1[[Example_Notification, Example, Version=0_0_0_1, Culture=neutral, PublicKeyToken=null]]
```

It should be something like this:

```csharp
Factor_MediatR_ICancellableAsyncNotificationHandler__Example_Notification__
```