How to Convert Null value To Visibility in C++/WinRT ?

using System;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Data;

namespace AppUIBasics.Common
{
    public class NullToVisibilityConverter : IValueConverter
    {
        public Visibility NullValue { get; set; } = Visibility.Collapsed;
        public Visibility NonNullValue { get; set; } = Visibility.Visible;


        public object Convert(object value, Type targetType, object parameter, string language)
        {
            return (value == null) ? NullValue : NonNullValue;
        }

        public object ConvertBack(object value, Type targetType, object parameter, string language)
        {
            throw new NotImplementedException();
        }
    }
}

namespace TD2_WinUI3
{
	[default_interface]
	runtimeclass NullToVisibilityConverter : [default] Windows.UI.Xaml.Data.IValueConverter
	{
		NullToVisibilityConverter();
		static Windows.UI.Xaml.DependencyProperty NullValueProperty{ get; };
		static Windows.UI.Xaml.DependencyProperty NonNullValueProperty{ get; };
		IInspectable NullValue;
		IInspectable NonNullValue;
	}
}

#pragma once

#include "winrt/Microsoft.UI.Xaml.h"
#include "winrt/Microsoft.UI.Xaml.Markup.h"
#include "winrt/Microsoft.UI.Xaml.Controls.Primitives.h"
#include "NullToVisibilityConverter.g.h"

namespace winrt::TD2_WinUI3::implementation
{
    struct NullToVisibilityConverter : NullToVisibilityConverterT<NullToVisibilityConverter>
    {
        NullToVisibilityConverter() 
        {
            NullValue(winrt::box_value(Microsoft::UI::Xaml::Visibility::Collapsed));
            NonNullValue(winrt::box_value(Microsoft::UI::Xaml::Visibility::Visible));
        };

        IInspectable NullValue() { return  GetValue(m_nullValueProperty); };
        void NullValue(IInspectable const& value) { SetValue(m_nullValueProperty, value); };
        static DependencyProperty NullValueProperty() { return m_nullValueProperty; };

        IInspectable NonNullValue() { return  GetValue(m_nonNullValueProperty); };
        void NonNullValue(IInspectable const& value) { SetValue(m_nonNullValueProperty, value); };
        static DependencyProperty NonNullValueProperty() { return m_nonNullValueProperty; };

        Windows::Foundation::IInspectable Convert(Windows::Foundation::IInspectable const& value, Windows::UI::Xaml::Interop::TypeName const& targetType, Windows::Foundation::IInspectable const& parameter, hstring const& language);
        Windows::Foundation::IInspectable ConvertBack(Windows::Foundation::IInspectable const& value, Windows::UI::Xaml::Interop::TypeName const& targetType, Windows::Foundation::IInspectable const& parameter, hstring const& language);

    private:
        static DependencyProperty m_nullValueProperty;
        static DependencyProperty m_nonNullValueProperty;
    };
}

namespace winrt::TD2_WinUI3::factory_implementation
{
    struct NullToVisibilityConverter : NullToVisibilityConverterT<NullToVisibilityConverter, implementation::NullToVisibilityConverter>
    {
    };
}

#include "pch.h"
#include "NullToVisibilityConverter.h"
#include "NullToVisibilityConverter.g.cpp"

using namespace winrt::Windows;
using namespace winrt::Windows::UI::Xaml;

namespace winrt::TD2_WinUI3::implementation
{
    DependencyProperty NullToVisibilityConverter::m_nullValueProperty = DependencyProperty::Register(L"NullValue", winrt::xaml_typename<IInspectable>(), winrt::xaml_typename <TD2_WinUI3::NullToVisibilityConverter>(), PropertyMetadata(nullptr));
    DependencyProperty NullToVisibilityConverter::m_nonNullValueProperty = DependencyProperty::Register(L"NonNullValue", winrt::xaml_typename<IInspectable>(), winrt::xaml_typename <TD2_WinUI3::NullToVisibilityConverter>(), PropertyMetadata(nullptr));


    Windows::Foundation::IInspectable NullToVisibilityConverter::Convert(Windows::Foundation::IInspectable const& value, Windows::UI::Xaml::Interop::TypeName const& /* targetType */, Windows::Foundation::IInspectable const&  parameter , hstring const& /* language */)
    {
        // Retrieve the value as  String.
        return (value == nullptr) ? NullValue() : NonNullValue();
    }

    Windows::Foundation::IInspectable NullToVisibilityConverter::ConvertBack(Windows::Foundation::IInspectable const& /* value */, Windows::UI::Xaml::Interop::TypeName const& /* targetType */, Windows::Foundation::IInspectable const& /* parameter */, hstring const& /* language */)
    {
        throw hresult_not_implemented();
    }
}