为什么在采用对象初始化器时使用(int？)null？

public class MyClass
{
    public int MyProperty { get; set; }
    public string AnotherProperty { get; set; }
}

var myInstance = new MyClass
{
    MyProperty = 10,
    AnotherProperty = "Hello"
};

var myInstance = new MyClass
{
    MyProperty = (int?)null,
    AnotherProperty = "Hello"
};

public class MyClass
{
    public int? MyProperty { get; set; }
    public string AnotherProperty { get; set; }
}

var myInstance = new MyClass
{
    MyProperty = (int?)null,
    AnotherProperty = "Hello"
};