RSRP-288391: Always-false expression is not detected for results of arithmetic operators on nullable integers

using System;

class Program
{
    static void Foo(int? x, int? y)
    {
        if (x.HasValue && y.HasValue)
        {
            return;
        }

        int? z = x + y;
        if(z.HasValue) // 'Expression is always false' is not detected
        {
            Console.WriteLine();
        }
    }
}