SA1119 patches may cause code to be unenforceable

[ymh199478]

The following code causes SA1119：

public void Foo(string str, int num)
{
    if (!(str is null) && num > 10)
    {
    }
}

After repairing according to the patch：

public void Foo(string str, int num)
{
    if (!str is null && num > 10)
    {
    }
}

Code: !str is null it is invalid

[sharwell]

Duplicate of #2372

[ymh199478]

thanks