Custom Indexable item type for my non-sitecore data

JsonIndexableItem.cs

using System;
using System.Collections.Generic;
using System.Globalization;
using MyCustomModels.Flights.Model;
using Sitecore.ContentSearch;
using Sitecore.ContentSearch.Converters;
using Sitecore.Data;
using Sitecore.Diagnostics;

namespace Business.Search.Json
{
    public class IndexableJsonField : IIndexableDataField
    {
        public string Name { get; set; }
        public string TypeKey { get; set; }
        public Type FieldType { get; set; }
        public object Value { get; set; }
        public object Id { get; set; }
    }

    public class JsonIndexableItem : IHierarchicalIndexable, IIndexable, IIndexableBuiltinFields
    {
        public virtual IIndexFieldStorageValueFormatter IndexFieldStorageValueFormatter { get; set; }

        public JsonIndexableItem(KeyValuePair<string, FlightDetail> item)
        {            
            Assert.ArgumentNotNull(item, nameof(item));
            this.Item = item;
        }
        public virtual KeyValuePair<string, FlightDetail> Item { get; protected set; }

        public static implicit operator JsonIndexableItem(KeyValuePair<string, FlightDetail> item)
        {
            return item.Value == null ? (JsonIndexableItem)null : new JsonIndexableItem(item);
        }

        public static implicit operator KeyValuePair<string, FlightDetail>(JsonIndexableItem indexable)
        {
            return indexable == null ? new KeyValuePair<string, FlightDetail>() : indexable.Item;
        }
        
        public virtual IIndexableId Id
        {
            get
            {
                return new IndexableId<string>(this.Item.Key.Replace(":", ""));
            }
        }

        public virtual IIndexableUniqueId UniqueId
        {
            get
            {
                return new IndexableUniqueId<string>(this.Item.Key.Replace(":", ""));
            }
        }

        public virtual string DataSource
        {
            get
            {
                return "Fids Json";
            }
        }

        public virtual string AbsolutePath
        {
            get
            {
                return "/sitecore/content/Home/passengers/flights/departures-and-arrivals/" + this.Item.Key.Replace(":", "");
            }
        }

        public virtual CultureInfo Culture
        {
            get
            {                
                return CultureInfo.CurrentCulture;
            }
        }

        public virtual IEnumerable<IIndexableDataField> Fields
        {
            get
            {
                var fieldList = new List<IIndexableDataField>();
                var fObj = this.Item.Value;
                var itemType = fObj.GetType();
                foreach (var propertyInfo in itemType.GetProperties())
                {
                    if (!propertyInfo.CanRead)
                    {
                        continue;
                    }

                    var fName = propertyInfo.Name;
                    var fValue = propertyInfo.GetValue(fObj);
                    Type fType = Type.GetType("System.String"); //map to a string to keep things simple 
                    var newField = new IndexableJsonField{ Name = fName, Value = fValue, FieldType = fType, Id = fName, TypeKey = "System.String" };
                    fieldList.Add(newField);
                }
                return fieldList;
            }
        }

        public virtual void LoadAllFields()
        {
            //not needed, specific to Sitecore items
        }

        public virtual IIndexableDataField GetFieldById(object fieldId)
        {
            var fObj = this.Item.Value;
            var itemType = fObj.GetType();
            foreach (var propertyInfo in itemType.GetProperties())
            {
                if (!propertyInfo.CanRead)
                {
                    continue;
                }
                if (propertyInfo.Name != fieldId.ToString())
                {
                    continue;
                }

                var fName = propertyInfo.Name;
                var fValue = propertyInfo.GetValue(fObj);
                var fType = propertyInfo.GetType();
                return new IndexableJsonField { Name = fName, Value = fValue, FieldType = fType, Id = fName, TypeKey = fType.FullName };
            }
            return null;
        }

        public virtual IIndexableDataField GetFieldByName(string fieldName)
        {
            var fObj = this.Item.Value;
            var itemType = fObj.GetType();
            foreach (var propertyInfo in itemType.GetProperties())
            {
                if (!propertyInfo.CanRead)
                {
                    continue;
                }
                if (propertyInfo.Name != fieldName)
                {
                    continue;
                }

                var fName = propertyInfo.Name;
                var fValue = propertyInfo.GetValue(fObj);
                var fType = propertyInfo.GetType();
                return new IndexableJsonField { Name = fName, Value = fValue, FieldType = fType, Id = fName, TypeKey = fType.FullName };
            }
            return null;
        }

        string IIndexableBuiltinFields.ID
        {
            get
            {
                return this.Item.Key;
            }
        }

        string IIndexableBuiltinFields.Database
        {
            get
            {
                return "web";
            }
        }

        string IIndexableBuiltinFields.Language
        {
            get
            {
                return "en-au";
            }
        }

        object IIndexableBuiltinFields.TemplateId
        {
            get
            {
                //a dummy template id, not actually used
                return (object)new ID("{9B0146DA-B70B-47F7-BF2B-63839858C068}");
            }
        }

        bool IIndexableBuiltinFields.IsLatestVersion { get; set; }

        int IIndexableBuiltinFields.Version
        {
            get
            {
                return 1;
            }
        }

        object IIndexableBuiltinFields.Group
        {
            get
            {
                return (object)this.Item.Key;
            }
        }

        bool IIndexableBuiltinFields.IsClone
        {
            get
            {
                return false;
            }
        }

        string IIndexableBuiltinFields.FullPath
        {
            get
            {
                return "/sitecore/content/Home/passengers/flights/departures-and-arrivals/" + this.Item.Key.Replace(":", "").ToLower();
            }
        }

        string IIndexableBuiltinFields.Name
        {
            get
            {
                return this.Item.Key;
            }
        }

        string IIndexableBuiltinFields.DisplayName
        {
            get
            {
                return this.Item.Key;
            }
        }

        object IIndexableBuiltinFields.Parent
        {
            get
            {
                return null;
            }
        }

        string IIndexableBuiltinFields.CreatedBy
        {
            get
            {
                return "sitecore\admin";
            }
        }

        string IIndexableBuiltinFields.UpdatedBy
        {
            get
            {
                return "sitecore\admin";
            }
        }

        string IIndexableBuiltinFields.TemplateName
        {
            get
            {
                return "FlightInfo";
            }
        }

        DateTime IIndexableBuiltinFields.CreatedDate
        {
            get
            {
                return DateTime.Now;
            }
        }

        DateTime IIndexableBuiltinFields.UpdatedDate
        {
            get
            {
                return DateTime.Now;
            }
        }

        IEnumerable<string> IIndexableBuiltinFields.Paths
        {
            get
            {
                return new List<string>(); //not used
            }
        }
    }
}