getPopulatedAttributes function Null safety

Implementation

List<Attribute> getPopulatedAttributes(
  final Product product,
  final List<String> attributeIds,
  final List<String> excludedAttributeIds,
) {
  final List<Attribute> result = <Attribute>[];
  final Map<String, Attribute> attributes = product.getAttributes(attributeIds);
  for (final String attributeId in attributeIds) {
    if (excludedAttributeIds.contains(attributeId)) {
      continue;
    }
    Attribute? attribute = attributes[attributeId];
// Some attributes selected in the user preferences might be unavailable for some products
    if (attribute == null) {
      continue;
    } else if (attribute.id == Attribute.ATTRIBUTE_ADDITIVES) {
// TODO(stephanegigandet): remove that cheat when additives are more standard
      final List<String>? additiveNames = product.additives?.names;
      attribute = Attribute(
        id: attribute.id,
        title: attribute.title,
        iconUrl: attribute.iconUrl,
        descriptionShort: additiveNames == null ? '' : additiveNames.join(', '),
      );
    }
    result.add(attribute);
  }
  return result;
}