Umbraco Multinode picker2 UDI's to GUID for examine

ContentEvents.cs

public class ContentPublishEvents : IApplicationEventHandler
    {
        public void OnApplicationInitialized(UmbracoApplicationBase umbracoApplication, ApplicationContext applicationContext)
        {
        }

        public void OnApplicationStarting(UmbracoApplicationBase umbracoApplication, ApplicationContext applicationContext)
        {
        }

        public void OnApplicationStarted(UmbracoApplicationBase umbracoApplication, ApplicationContext applicationContext)
        {
            ExamineManager.Instance.IndexProviderCollection["ExternalIndexer"].GatheringNodeData += (sender, e) => ExternalIndexerGatheringNodeData(e);
        }       

        private static void ExternalIndexerGatheringNodeData(IndexingNodeEventArgs e)
        {
            if (e.IndexType != IndexTypes.Content) return;
            ConvertUdiToGuidStringField(e, "serviceTags");
            ConvertUdiToGuidStringField(e, "sectorTags");
        }

        private static void ConvertUdiToGuidStringField(IndexingNodeEventArgs e, string field)
        {
            if (!e.Fields.ContainsKey(field)) return;
            var raw = e.Fields[field];
            if (string.IsNullOrWhiteSpace(raw)) return;

            var guids = raw.Replace("umb://document/", " ", StringComparison.InvariantCultureIgnoreCase).Replace(",", string.Empty, StringComparison.InvariantCultureIgnoreCase).Trim();
            e.Fields.Add(field + "Guid", string.Join(" ", guids));
        }
    }