Cannot inherit System.ServiceModel.Security.Tokens.SecurityTokenParameters

**Describe the bug**
I am trying to move from .NET Framework to .NET 6 and I get errors with overriding members/methods and the error "Cannot access internal constructor 'SecurityTokenParameters()' here". What I've found there is a partial class of this class in the System.ServiceModel.Primitives.Ref which has an internal constructor, while the class in System.ServiceModel.Primitives has an protected constructor. Is this a bug or made with intention for some reason?

**To Reproduce**
Steps to reproduce the behavior:
1. Create a .NET 6 class library project
2. Reference System.ServiceModel.Primitives 6.0.0-preview1.23060.3
3. Create a class

```
public class CustomSecurityTokenParameters : System.ServiceModel.Security.Tokens.SecurityTokenParameters
{
public CustomSecurityTokenParameters()
{ }

protected override SecurityTokenParameters CloneCore()
{
throw new NotImplementedException();
}
}
```

**Expected behavior**
Be possible to create a class which inherits from SecurityTokenParameters from my project.