Bug: InvalidCastException because failed to create a CCW in AOT for IAsyncOperation<>

Description

An WinRT API described below:

public static class MyClass
{
    public static IAsyncOperation<IReadOnlyList<MyData>> TestAsync ()
    {
        return AsyncInfo.Run((CancelToken) => new ReadOnlyCollection<MyData>([new MyData()]));
    }
}

Everything OK if AOT not enabled. However, once AOT enabled. The caller will get an InvalidCastException. Failed to create a CCW for ReadOnlyCollection<MyData>.

After adding the code below, it works again in AOT.

[assembly: GeneratedWinRTExposedExternalType(typeof(ReadOnlyCollection<MyData>))]

I want to know will this exception be fixed in CsWinRT 2.3 and adding GeneratedWinRTExposedExternalType for the generic collection is just a temporary workaround? Or it's not a bug and we should always use GeneratedWinRTExposedExternalType to every generic collection variant to make it works in AOT?

What is the difference for my case after #1877 collection expression implemented in CsWinRT 2.3 ?

public static IAsyncOperation<IReadOnlyList<MyData>> TestAsync ()
{
    // After CsWinRT 2.3, this will also works?
    // Will we still need GeneratedWinRTExposedExternalType(typeof(ReadOnlyCollection<MyData>)) ?
    return AsyncInfo.Run((CancelToken) => [new MyData()]);
    // return AsyncInfo.Run((CancelToken) => new ReadOnlyCollection<MyData>([new MyData()]));
}

Steps To Reproduce

See code above

Expected Behavior

Should generate the CCW automatically for anything like

IAsyncOperation<IReadOnlyList<>>
IAsyncOperation<IList<>>
IAsyncOperation<IEnumerable<>>
IAsyncOperation<ICollection<>>

Version Info

Microsoft.Windows.CsWinRT 2.2.0

Additional Context

No response

Reproduce the AOT failure with the IAsyncOperation<IReadOnlyList> sample and compare it with the GeneratedWinRTExposedExternalType workaround. Trace the CCW generation path for ReadOnlyCollection, then compare the collection-expression case described in the issue. Done means the supported generic collection variants create CCWs automatically, or the required workaround is clearly documented and covered by a regression test.