Adapt to existing object not work when have readonly property

Please help.
```c#
void Main()
{
	var a1=new Foo(){Id=3,Name="aa"};
	var a2=new Foo(){Id=3};
	a1.Adapt(a2);
	a2.Name.Dump(); // will got null
}

class Foo(){
	public int Id {get;set;}
	public string Name{get;set;}
	public string Prop {get;} //when have setter, no problem
}
```