继承LIst 的类JSON序列化，无法序列化属性的问题

/// <summary>
    /// Paged list
    /// </summary>
    /// <typeparam name="T">T</typeparam>
    [JsonObject(MemberSerialization = MemberSerialization.OptIn)] 
    public class PagedList<T> : List<T>, IPagedList<T> 
    {
        /// <summary>
        /// Ctor
        /// </summary>
        /// <param name="source">source</param>
        /// <param name="pageIndex">Page index</param>
        /// <param name="pageSize">Page size</param>
        /// <param name="getOnlyTotalCount">A value in indicating whether you want to load only total number of records. Set to "true" if you don't want to load data from database</param>
        public PagedList(IQueryable<T> source, int pageIndex, int pageSize, bool getOnlyTotalCount = false)
        {
            var total = source.Count();
            this.TotalCount = total;
            this.TotalPages = total / pageSize;

            if (total % pageSize > 0)
                TotalPages++;

            this.PageSize = pageSize;
            this.PageIndex = pageIndex;
            if (getOnlyTotalCount)
                return;
            this.AddRange(source.Skip(pageIndex * pageSize).Take(pageSize).ToList());
        }

        /// <summary>
        /// Ctor
        /// </summary>
        /// <param name="source">source</param>
        /// <param name="pageIndex">Page index</param>
        /// <param name="pageSize">Page size</param>
        public PagedList(IList<T> source, int pageIndex, int pageSize)
        {
            TotalCount = source.Count;
            TotalPages = TotalCount / pageSize;

            if (TotalCount % pageSize > 0)
                TotalPages++;

            this.PageSize = pageSize;
            this.PageIndex = pageIndex;
            this.AddRange(source.Skip(pageIndex * pageSize).Take(pageSize).ToList());
        }

        /// <summary>
        /// Ctor
        /// </summary>
        /// <param name="source">source</param>
        /// <param name="pageIndex">Page index</param>
        /// <param name="pageSize">Page size</param>
        /// <param name="totalCount">Total count</param>
        public PagedList(IEnumerable<T> source, int pageIndex, int pageSize, int totalCount)
        {
            TotalCount = totalCount;
            TotalPages = TotalCount / pageSize;

            if (TotalCount % pageSize > 0)
                TotalPages++;

            this.PageSize = pageSize;
            this.PageIndex = pageIndex;
            this.AddRange(source);
        }

        /// <summary>
        /// Page index
        /// </summary> 
        [JsonProperty]
        public int PageIndex { get;   }

        /// <summary>
        /// Page size
        /// </summary> 
        [JsonProperty]
        public int PageSize { get;   }

        /// <summary>
        /// Total count
        /// </summary> 
        [JsonProperty]
        public int TotalCount { get;  }

        /// <summary>
        /// Total pages
        /// </summary> 
        [JsonProperty]
        public int TotalPages { get;  }

        /// <summary>
        /// Has previous page
        /// </summary>
        [JsonProperty]
        public bool HasPreviousPage
        {
            get {
                return PageIndex > 0;
            }
            set {

            }
        }

        /// <summary>
        /// Has next page
        /// </summary>
        [JsonProperty]
        public bool HasNextPage
        {
            get
            {
                return PageIndex + 1 < TotalPages;
            } 
        }
        [JsonProperty]
        public List<T> Items
        {
            get
            {
                return this.ToList();
            } 
        }
    }