对于下面的代码，stream1和stream2单独运行良好，我可以看到输出，但是连接的流根本不记录任何内容。我觉得这和join窗口有关，但是来自两个流的数据几乎是同时进入的。

val stream = builder.stream(stringSerde, byteArraySerde, "topic")

val stream1 = stream
  .filter((key, value) => somefilter(key, value))
  .through(stringSerde, byteArraySerde, "topic1")

val stream2 = stream
  .filter((key, value) => someotherfilter(key, value))
  .through(stringSerde, byteArraySerde, "topic2")

val joinedStream = stream1
  .join(stream2, (value1: Array[Byte], value2: Array[Byte]) => {
    println("wont print anything")
    return somerandomdata
  },
  JoinWindows.of("othertopic").within(10000L),
  stringSerde, byteArraySerde, byteArraySerde)