Solr-C#查询排序字段莫名追加's'问题排查求助

我们的Solr排序功能无法正常工作，经排查发现生成的查询语句末尾为sort=date_tdts%20desc，而正确格式应为sort=date_tdt%20desc（多了一个额外的's'）。我们不清楚代码中该额外's'的来源，以下是相关代码片段，请求排查原因：

索引字段配置 #

[IndexField("date_tdt")]
public DateTime Date { get; set; }

查询生成代码 #

var orderExpression = searchAdapter.MapFilterToOrder(query, out bool orderByDescending);

var resultsQueryable = providerSearchContext.GetQueryable<TSearchItem>()
    .Where(basePredicate);

if(query.Filters != null)
{
    var queryPredicate = CombinePredicates(query.Filters.Select(searchAdapter.MapFilterToPredicate));
    resultsQueryable = resultsQueryable.Where(queryPredicate);
}

if (orderExpression != null)
{
    resultsQueryable = orderByDescending
        ? resultsQueryable.OrderByDescending(orderExpression)
        : resultsQueryable.OrderBy(orderExpression);
}

MapFilterToOrder方法实现 #

public virtual Expression<Func<ArticleSearchResultItem, object>> MapFilterToOrder(SearchQuery query,
    out bool @descending)
{
    @descending = true;

    return x => x.Date;
}

内容的提问来源于stack exchange，提问作者Erica Stockwell-Alpert