"Protected Interface Method Polymorphism"

interface IExampleInterface {
	protected void Test() => Console.WriteLine("Interface");

    void InvokeTest() => Test();
}

class ExampleClass : IExampleInterface {
	void IExampleInterface.Test() => Console.WriteLine("Class"); // This MUST be implemented explicitly
}

class Program {
    static void Main() {
        IExampleInterface e = new ExampleClass();

        e.InvokeTest(); // Prints "Class"
    }
}


Code snippet taken from "Two Decades of C#: A Reference - C# 8".