我在加入带有globalktable的kstream时遇到了一个问题，非常感谢您的帮助。
考虑到Kafka的两个主题 orders 以及 customers :
订单

"1"     {"ID":"1","Name":"Myorder1","CustID":"100"}

"2"     {"ID":"2","Name":"MyOrder2","CustID":"200"}

客户

"100"   {"CustID":"100","CustName":"Customer1"}

"200"   {"CustID":"200","CustName":"Customer2"}

要求是用客户名称丰富订单流

"1"     {"ID":"1","Name":"Myorder1","CustID":"100","CustName":"Customer1"}

"2"     {"ID":"2","Name":"MyOrder2","CustID":"200","CustName":"Customer2"}}

我正在尝试以下方法：
从 orders 主题
从 customers 主题
构建另一个连接orders和customers的流（在customer表中查找order.custid）

KStream<String, EnrichedOrder> enrichedstreams = orders.join(
    customers,
    new KeyValueMapper<String, Order, String>() {            
        @Override
        public String apply(String key, Order value) {
           return value.CustID;
        }
    },
    new ValueJoiner<Order,Customer, EnrichedOrder>() {
        @Override
        public EnrichedOrder apply(Order order, Customer customer) {
            EnrichedOrder eorder = new EnrichedOrder();
            eorder.CustID = order.CustID;
            eorder.CustName = customer.CustName;
            eorder.ID = order.ID;
            eorder.Name = order.Name;           
            return eorder;
        }
    }
);

但它不会给出任何结果，也不会抛出任何异常。
当使用 leftJoin ，我得到一个客户的nullpointer异常。
请让我知道，如果你遇到了类似的问题，并建议如何解决这个问题。