如何使用RavenDB 3.5创建一个模拟内部连接的索引？

// 定义索引
public class InnerJoinIndex : AbstractIndexCreationTask<Order, InnerJoinIndex.Result>
{
    public class Result
    {
        public string OrderId { get; set; }
        public string CustomerName { get; set; }
        public string ProductName { get; set; }
    }

    public InnerJoinIndex()
    {
        Map = orders => from order in orders
                        let customer = LoadDocument<Customer>(order.CustomerId)
                        let product = LoadDocument<Product>(order.ProductId)
                        select new
                        {
                            OrderId = order.Id,
                            CustomerName = customer.Name,
                            ProductName = product.Name
                        };
    }
}

// 执行查询
using (var session = documentStore.OpenSession())
{
    var results = session.Query<InnerJoinIndex.Result, InnerJoinIndex>()
                        .Where(x => x.CustomerName == "John" && x.ProductName == "Widget")
                        .ToList();

    foreach (var result in results)
    {
        Console.WriteLine($"Order ID: {result.OrderId}, Customer Name: {result.CustomerName}, Product Name: {result.ProductName}");
    }
}