Необязательное свойство в классе C#

Optional property
I want to create a class that has an optional property. I don't want to create a subclass
Example
public class MyClass
    {
        public MyClass( int extraPoperty)
        {
            // Something like this
            if(extraPoperty==1)
            public int ExtraPoperty { get;  set; }

        }

        public int EntityId { get;  set; }
    }

Is this possible?