ExtendedApiContentResponseBuilder.cs

public class ExtendedApiContentResponseBuilder : LayoutBuilderBase<IApiContentResponse>, IApiContentResponseBuilder
{
    private readonly IApiContentRouteBuilder _apiContentRouteBuilder;

    public ExtendedApiContentResponseBuilder(
        IApiContentNameProvider apiContentNameProvider,
        IApiContentRouteBuilder apiContentRouteBuilder,
        IOutputExpansionStrategyAccessor outputExpansionStrategyAccessor,
        IEnumerable<IComponentResolver> componentResolvers,
        IApiPublishedContentCache apiPublishedContentCache)
        : base(apiContentNameProvider, apiContentRouteBuilder, outputExpansionStrategyAccessor, componentResolvers, apiPublishedContentCache)
    {
        _apiContentRouteBuilder = apiContentRouteBuilder;
    }

    protected override IApiContentResponse Create(IPublishedContent content, string name, IApiContentRoute route, IDictionary<string, object?> properties)
    {
        var cultures = GetCultures(content);

        return new ApiContentResponse(
            content.Key,
            name,
            content.ContentType.Alias,
            content.CreateDate,
            content.UpdateDate,
            route,
            properties,
            cultures);
    }

    /// <summary>
    /// Copied from the original ApiContentResponseBuilder
    /// </summary>
    private Dictionary<string, IApiContentRoute> GetCultures(IPublishedContent content)
    {
        var routesByCulture = new Dictionary<string, IApiContentRoute>();
        foreach (var publishedCultureInfo in content.Cultures.Values)
        {
            if (publishedCultureInfo.Culture.IsNullOrWhiteSpace())
            {
                continue;
            }

            var cultureRoute = _apiContentRouteBuilder.Build(content, publishedCultureInfo.Culture);
            if (cultureRoute == null)
            {
                continue;
            }

            routesByCulture[publishedCultureInfo.Culture] = cultureRoute;
        }

        return routesByCulture;