is generic method override supported?

This code works in .NET 3.5, but not in Unity 5.3.4f1

Code (CSharp):

1. public class ClassA
2. {
3.     /// <summary>
4.     /// works fine
5.     /// </summary>
6.     public virtual T2 Example<T1, T2>(T1 val) where T2 : T1
7.     {
8.         return (T2)val;
9.     }
10. }
11. public class ClassB : ClassA
12. {
13.     /// <summary>
14.     /// error here
15.     /// </summary>
16.     public override T2 Example<T1, T2>(T1 val)
17.     {
18.         return base.Example<T1, T2>(val);
19.     }
20. }

I get : error CS0309: The type `T2' must be convertible to `T1' in order to use it as parameter `T2' in the generic type or method `ClassA.Example<T1,T2>(T1)'

 

make sure the override version is also using the "where T2 : T1" contraint.