Which pattern to choose?

Question

Software design

There is a package, the package has a class, Stopwatch, it does not implement any interface. It is necessary to inject it in certain places in order to monitor the load, but there is no interface, and it is harmful to inject the implementation, we lose abstraction.
What pattern is suitable in such cases?
When you need to inject a class from vendor that comes without an interface.

Answer 1

Make a decorator over this class, the decorator has an interface and inject it.
You are many times more experienced than me, why didn’t it come to you at the click of a finger?