Field Is No Longer Indexed in the Sitecore Items

using System;
using Sitecore.ContentSearch.ComputedFields;
using Sitecore.ContentSearch;
using Sitecore;
using Sitecore.Data.Items;
using Sitecore.Data.Fields;
using Sitecore.Data;
using Coveo.Framework.CNL;
using Coveo.Framework.Log;
using Coveo.Framework.Pipelines;
using Coveo.Framework.Processor;
using Coveo.SearchProvider.Pipelines;
using Coveo.AbstractLayer.Security;
using Coveo.AbstractLayer.RepositoryItem;
using Coveo.AbstractLayer.FieldManagement;
using System.Linq;
using Coveo.Framework.Collections;
using System.Collections.Generic;

namespace Coveo.AddLegacyFields
{

    public class AddLegacyFieldsMetadata : IProcessor<CoveoPostItemProcessingPipelineArgs>
    {
        private static readonly ILogger s_Logger = CoveoLogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);

        public bool AddBaseItemFields { get; set; } = true;
        public bool AddLayoutFields { get; set; } = true;
        public bool AddMediaItemFields { get; set; } = true;
        public bool AddItemUriFields { get; set; } = true;
        public bool AddPathsFields { get; set; } = true;
        public bool AddStatisticsFields { get; set; } = true;

        public void Process(CoveoPostItemProcessingPipelineArgs p_Args)
        {
            SitecoreIndexableItem sii = p_Args.Item as SitecoreIndexableItem;
            if (sii != null) {
                p_Args.OutputCoveoItems.Select(item => {
                    s_Logger.Debug("Adding legacy fields for item ID: " + item.UniqueId.ToString());
                    return new LegacyMetadataFiller(item);
                }).ForEach(filler => {
                    if (AddBaseItemFields) filler.AddBaseItemMetadata(sii);
                    if (AddLayoutFields) filler.AddLayoutMetadata(sii);
                    if (AddMediaItemFields) filler.AddMediaItemMetadata(sii);
                    if (AddItemUriFields) filler.AddItemUriMetadata(sii);
                    if (AddPathsFields) filler.AddPathsMetadata(sii);
                    if (AddStatisticsFields) filler.AddStatisticsMetadata(sii);
                });
            }
        }
    }

    internal class LegacyMetadataFiller
    {
        private readonly CoveoIndexableItem m_CoveoItem;
        public LegacyMetadataFiller(CoveoIndexableItem p_IndexableItem)
        {
            m_CoveoItem = p_IndexableItem;
        }

        public void AddBaseItemMetadata(Item p_Item)
        {
            FillWithLegacyItemMetadata(p_Item);
        }

        private void FillWithLegacyItemMetadata(Item p_Item)
        {
            m_CoveoItem.SetMetadata("BranchId", p_Item.BranchId.ToString());
            m_CoveoItem.SetMetadata("DatabaseName", p_Item.Database?.Name);
            m_CoveoItem.SetMetadata("DisplayName", p_Item.DisplayName);
            m_CoveoItem.SetMetadata("HasClones", p_Item.HasClones ? "1" : "0");
            m_CoveoItem.SetMetadata("IsClone", p_Item.IsClone ? "1" : "0");
            m_CoveoItem.SetMetadata("IsItemClone", p_Item.IsItemClone ? "1" : "0");
            m_CoveoItem.SetMetadata("Key", p_Item.Key);
            m_CoveoItem.SetMetadata("Empty", p_Item.Empty ? "1" : "0");
            m_CoveoItem.SetMetadata("HasChildren", p_Item.HasChildren ? "1" : "0");
            m_CoveoItem.SetMetadata("ID", p_Item.ID.Guid.ToString());
            m_CoveoItem.SetMetadata("Modified", p_Item.Modified ? "1" : "0");
            m_CoveoItem.SetMetadata("Name", p_Item.Name);
            m_CoveoItem.SetMetadata("OriginatorID", p_Item.OriginatorId.ToString());
            m_CoveoItem.SetMetadata("TemplateID", p_Item.TemplateID.Guid.ToString());
            m_CoveoItem.SetMetadata("TemplateName", p_Item.TemplateName);

            if (p_Item.Language != null) m_CoveoItem.SetMetadata("Language", p_Item.Language.ToString());
            if (p_Item.Version != null) m_CoveoItem.SetMetadata("Version", p_Item.Version.ToString());
        }

        public void AddLayoutMetadata(Item p_Item)
        {
            LayoutItem layout = p_Item?.Visualization?.Layout;
            if (layout != null) FillWithLegacyLayoutMetadata(layout);
        }

        private void FillWithLegacyLayoutMetadata(LayoutItem p_Layout)
        {
            m_CoveoItem.SetMetadata("LayoutControl", p_Layout.Control);
            m_CoveoItem.SetMetadata("LayoutDisplayName", p_Layout.DisplayName);
            m_CoveoItem.SetMetadata("LayoutFilePath", p_Layout.FilePath);
            m_CoveoItem.SetMetadata("LayoutControl", p_Layout.Control);
            m_CoveoItem.SetMetadata("LayoutName", p_Layout.Name);
        }

        public void AddMediaItemMetadata(Item p_Item)
        {
            if (p_Item.Paths.IsMediaItem) {
                MediaItem mediaItem = p_Item;
                if (mediaItem != null) FillWithLegacyMediaItemMetadata(mediaItem);
            }
        }

        private void FillWithLegacyMediaItemMetadata(MediaItem p_Media)
        {
            m_CoveoItem.SetMetadata("Alt", p_Media.Alt);
            m_CoveoItem.SetMetadata("Extension", p_Media.Extension);
            m_CoveoItem.SetMetadata("FileBased", p_Media.FileBased);
            m_CoveoItem.SetMetadata("FilePath", p_Media.FilePath);
            m_CoveoItem.SetMetadata("Description", p_Media.Description);
            m_CoveoItem.SetMetadata("Size", p_Media.Size);
            m_CoveoItem.SetMetadata("Title", p_Media.Title);

            foreach (KeyValuePair<string, string> metadata in p_Media.GetMetaData())
            {
                if (!String.IsNullOrEmpty(metadata.Key)) {
                    m_CoveoItem.SetMetadata(metadata.Key, metadata.Value);
                }
            }
        }

        public void AddItemUriMetadata(Item p_Item)
        {
            ItemUri uri = p_Item.Uri;
            if (uri != null) FillWithLegacyItemUriMetadata(uri);
        }

        private void FillWithLegacyItemUriMetadata(ItemUri p_Uri)
        {
            m_CoveoItem.SetMetadata("DataUri", p_Uri.ToDataUri()?.ToString());
            m_CoveoItem.SetMetadata("DefaultUri", p_Uri.ToString());
            m_CoveoItem.SetMetadata("UrlString", p_Uri.ToUrlString("")?.ToString());
        }

        public void AddPathsMetadata(Item p_Item) {
            ItemPath path = p_Item.Paths;
            if (path != null) FillWithLegacyPathsMetadata(path);
        }

        private void FillWithLegacyPathsMetadata(ItemPath p_Path)
        {
            m_CoveoItem.SetMetadata("ContentPath", p_Path.ContentPath);
            m_CoveoItem.SetMetadata("FullPath", p_Path.FullPath);
            m_CoveoItem.SetMetadata("IsContentItem", p_Path.IsContentItem ? "1" : "0");
            m_CoveoItem.SetMetadata("IsFullyQualified", p_Path.IsFullyQualified ? "1" : "0");
            m_CoveoItem.SetMetadata("IsMasterPart", p_Path.IsMasterPart ? "1" : "0");
            m_CoveoItem.SetMetadata("IsMediaItem", p_Path.IsMediaItem ? "1" : "0");
            m_CoveoItem.SetMetadata("LongID", p_Path.LongID);
            m_CoveoItem.SetMetadata("MediaPath", p_Path.MediaPath);
            m_CoveoItem.SetMetadata("ParentPath", p_Path.ParentPath);
        }

        public void AddStatisticsMetadata(Item p_Item)
        {
            ItemStatistics stats = p_Item.Statistics;
            if (stats != null) FillWithLegacyStatisticsMetadata(stats);
        }

        private void FillWithLegacyStatisticsMetadata(ItemStatistics p_Stats)
        {
            m_CoveoItem.SetMetadata("Created", p_Stats.Created);
            m_CoveoItem.SetMetadata("CreatedBy", p_Stats.CreatedBy);
            m_CoveoItem.SetMetadata("Revision", p_Stats.Revision);
            m_CoveoItem.SetMetadata("Updated", p_Stats.Updated);
            m_CoveoItem.SetMetadata("UpdatedBy", p_Stats.UpdatedBy);
        }
    }
}

<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/">
  <sitecore>
    <pipelines>
      <coveoPostItemProcessingPipeline>
        <!-- Ensure that the processor type attribute value below matches your compiled namespace and assembly name. -->
        <processor type="Coveo.AddLegacyFields.AddLegacyFieldsMetadata, AddLegacyFields" />
      </coveoPostItemProcessingPipeline>
      <coveoIndexingGetFields>
        <processor
          patch:before="processor[@type='Coveo.AbstractLayer.Processors.Indexing.Fields.IncludeFieldsFromConfigOnlyProcessor, Coveo.AbstractLayer']"
          type="Coveo.AbstractLayer.Processors.Indexing.Fields.AddCoveoFieldsProcessor, Coveo.AbstractLayer" />
      </coveoIndexingGetFields>
    </pipelines>
  </sitecore>
</configuration>