如何在NSubstitute中通过超类匹配参数来存根方法?

参考以下示例代码:

using NSubstitute;
using NUnit.Framework;

public class Class1
{
}

public class Class2
{
    public void Method(Class1 class1)
    {
    }
}

public class Class3 : Class1
{
}

[TestFixture]
public class ArgAnyTest
{
    [Test]
    public void Test()
    {
        var called = false;
        var class2 = Substitute.For<Class2>();
        class2.When(@this => @this.Method(Arg.Any<Class1>())).Do(invocation => called = true);

        class2.Method(new Class3());

        Assert.That(called, Is.EqualTo(true));
    }
}

断言失败,表明 Method 存根不匹配。我是否误解了 argument matcher 文件页,声称 Arg.Any 可用于“匹配特定子类型的任何参数”?