Partial property for AOT compatibility and MVVMTK0045

[King-Taz]

Using the code below

    [ObservableProperty]
    public int fontSize

    // This method called whenever `fontSize` changes.
    partial void OnFontSizeChanged(int value)
    {
        Preferences.Set("FontSize", value);
    }

I get the MVVMTK0045 error

The field *.*.fontSize using [ObservableProperty] will generate code that is not AOT compatible...
and a partial property should be used instead

So I change the codes as suggested in the documentation to

    [ObservableProperty]
    public partial int FontSize { get; set }

    // This method called whenever `fontSize` changes.
    partial void OnFontSizeChanged(int value)
    {
        Preferences.Set("FontSize", value);
    }

does not work and creates a different error "the partial property must have an implementation part". Any idea how to correct this issue?