Unable to use CreateMutualCertificateBindingElement

**Describe the bug**
I'm trying to migrate a project using WCF from .net 4.5 to .net 8
Must of it is already migrated but I am facing a problem in implementing the CreateMutualCertificateBindingElement functionality.
From the docs it looks like it should be supported in the latest .net 8 version with the latest 8.0 package

but when I try to implement it in the code it does not find the CreateMutualCertificateBindingElement implementation.

What am I missing here?
Any help will be greatly appreciated.

**To Reproduce**
Steps to reproduce the behavior:
1. Create a .net 8 console app
2. dotnet add package System.ServiceModel.Primitives --version 8.0.0
3. try to create the security binging element -
SecurityBindingElement security = SecurityBindingElement.CreateMutualCertificateBindingElement();