public void start() throws ModuleStartException {
        handlerMap = builder.build();
        builder = null;

        createTopicIfNeeded(handlerMap.keySet(), properties);
        for (KafkaConsumer<String, Bytes> consumer : consumers) {
            consumer.subscribe(handlerMap.keySet());
            consumer.seekToEnd(consumer.assignment());
            executor.submit(() -> runTask(consumer));
        }
    }
Configuring and initializing a KafkaConsumer client as a dispatcher to delivery Kafka Message to registered handler
by topic.
oap-server/server-fetcher-plugin/kafka-fetcher-plugin/src/main/java/org/apache/skywalking/oap/server/analyzer/agent/kafka/KafkaFetcherHandlerRegister.java