我已经定义了一个基本的Storm拓扑，其中包含Kafka的spout consumer（生产者是在Kafka的单独模块中创建的）。但是，当我运行应用程序时，我收到以下错误：

java.lang.RuntimeException: org.apache.kafka.common.errors.InvalidGroupIdException: To use the group management or offset commit APIs, you must provide a valid group.id in the consumer configuration.
    at org.apache.storm.utils.Utils$1.run(Utils.java:407) ~[storm-client-2.1.0.jar:2.1.0]
    at java.lang.Thread.run(Thread.java:748) [?:1.8.0_221]
Caused by: org.apache.kafka.common.errors.InvalidGroupIdException: To use the group management or offset commit APIs, you must provide a valid group.id in the consumer configuration.

如何设置组ID？我正在本地运行Storm 2.1.0版本。
下面是拓扑的代码：

val cluster = new LocalCluster()

val bootstrapServers = "localhost:9092"
val brokerHosts = new ZkHosts(bootstrapServers)
val topologyBuilder = new TopologyBuilder()

val spoutConfig = KafkaSpoutConfig.builder(bootstrapServers, "tweets").build()
topologyBuilder.setSpout("kafka_spout", new KafkaSpout(spoutConfig), 1)

val config = new Config()
cluster.submitTopology("kafkaTest", config, topologyBuilder.createTopology())