我遵循本指南向某些设备发送消息。关于构建发送请求的部分，它说：

// The topic name can be optionally prefixed with "/topics/".
String topic = "highScores";

// See documentation on defining a message payload.
Message message = Message.builder()
    .putData("score", "850")
    .putData("time", "2:45")
    .setTopic(topic)
    .build();

// Send a message to the devices subscribed to the provided topic.
String response = FirebaseMessaging.getInstance().send(message);
// Response is a message ID string.
System.out.println("Successfully sent message: " + response);

当我尝试导入消息类时，ide告诉我没有库，为什么？
可能已经弃用，但文档尚未更新？
谢谢