Nullability of reference types in type of parameter 'value' of 'object BooleanToVisibilityConverter.Convert(object value, Type targetType, object parameter, CultureInfo culture)' doesn't match implicitly implemented member 'object? IValueConverter.Convert(object? value, Type targetType, object? parameter, CultureInfo culture)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'parameter' of 'object BooleanToVisibilityConverter.Convert(object value, Type targetType, object parameter, CultureInfo culture)' doesn't match implicitly implemented member 'object? IValueConverter.Convert(object? value, Type targetType, object? parameter, CultureInfo culture)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'value' of 'object BooleanToVisibilityConverter.ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)' doesn't match implicitly implemented member 'object? IValueConverter.ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'parameter' of 'object BooleanToVisibilityConverter.ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)' doesn't match implicitly implemented member 'object? IValueConverter.ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'propertyName' of 'IEnumerable ValidatableBase.GetErrors(string propertyName)' doesn't match implicitly implemented member 'IEnumerable INotifyDataErrorInfo.GetErrors(string? propertyName)' (possibly because of nullability attributes).

Nullability of reference types in type of 'event EventHandler<DataErrorsChangedEventArgs> ValidatableBase.ErrorsChanged' doesn't match implicitly implemented member 'event EventHandler<DataErrorsChangedEventArgs>? INotifyDataErrorInfo.ErrorsChanged'.

Nullability of reference types in type of parameter 'value' of 'object NumberToColorConverter.Convert(object value, Type targetType, object parameter, CultureInfo culture)' doesn't match implicitly implemented member 'object? IValueConverter.Convert(object? value, Type targetType, object? parameter, CultureInfo culture)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'parameter' of 'object NumberToColorConverter.Convert(object value, Type targetType, object parameter, CultureInfo culture)' doesn't match implicitly implemented member 'object? IValueConverter.Convert(object? value, Type targetType, object? parameter, CultureInfo culture)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'value' of 'object NumberToColorConverter.ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)' doesn't match implicitly implemented member 'object? IValueConverter.ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)' (possibly because of nullability attributes).