即使timeToWait设置为1000毫秒，同步Paho MQTTClient仍挂在发布上

我们有一个Spring Boot应用程序，可将IoT传感器数据发布到AWS IoT。在负载下，我们的阻塞MqttClient无限期阻塞：

"taskScheduler-72" - Thread t@313
    java.lang.Thread.State: WAITING
    at java.lang.Object.wait(Native Method)
    - waiting on <7e7ec8a6> (a java.lang.Object)
    at java.lang.Object.wait(Object.java:502)
    at org.eclipse.paho.client.mqttv3.internal.Token.waitForResponse(Token.java:143)
    at org.eclipse.paho.client.mqttv3.internal.Token.waitForCompletion(Token.java:108)
    at org.eclipse.paho.client.mqttv3.MqttToken.waitForCompletion(MqttToken.java:67)
    at org.eclipse.paho.client.mqttv3.MqttClient.publish(MqttClient.java:570)
    at org.eclipse.paho.client.mqttv3.MqttClient.publish(MqttClient.java:562)
    at 
    ...

我们正在使用QOS 1：

try {
        mqttClient.publish(topic, payload, 1, false);
    } catch (MqttException e) {
        throw new PublishingException(e);
    }

我们正在使用spring-integration-mqtt：

<dependency>
    <groupId>org.springframework.integration</groupId>
    <artifactId>spring-integration-mqtt</artifactId>
    <version>4.2.1.RELEASE</version>
  </dependency>

我尝试将paho客户端更新为最新版本：

<dependency>
  <groupId>org.eclipse.paho</groupId>
  <artifactId>org.eclipse.paho.client.mqttv3</artifactId>
  <version>1.2.2</version>
  <scope>compile</scope>
</dependency>

并设置timeToWait，据我理解，如果发布请求在1000毫秒内未收到确认，则应该抛出MqttException：

mqttClient.setTimeToWait(1000);

为什么timeToWait不起作用？我们应该切换到AsyncMqttClient吗？