为什么不能让automapper参数化工作?

我想在哪里 _injectedInt 可能是声明的问题。我已经写了下面的测试和100被退回。

[TestClass]
public class UnitTest19
{
    [TestMethod]
    public void TestMethod1()
    {
        Mapper.Initialize(expression => expression.AddProfile(new MyProfile()));

        var queryableOfObjectA = new List<objectA>
        {
            new objectA
            {
                myNullableInt = 10
            }
        };

        var result = queryableOfObjectA.AsQueryable().ProjectTo<objectB>(new { _injectedInt = (int?)1 });

        var resultingValue = result.FirstOrDefault()?.myNullableInt;

        Assert.AreEqual(100, resultingValue);
    }
}

public class MyProfile : Profile
{
    public MyProfile()
    {
        int? _injectedInt = null;

        CreateMap<objectA, objectB>()
            .ForMember(e => e.myNullableInt, x => x.MapFrom(s => _injectedInt.HasValue ? 100 : 0));
    }
}

public class objectA
{
    public int myNullableInt { get; set; }
}

public class objectB
{
    public int myNullableInt { get; set; }
}