Kafka 2.5.0 Admin api，listOffset方法使用了什么时间戳？

import org.apache.kafka.clients.admin.*;
import java.util.*;
import java.util.concurrent.ExecutionException;

public class KafkaAdminExample {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        Properties props = new Properties();
        props.put(AdminClientConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
        AdminClient adminClient = AdminClient.create(props);

        ListOffsetsResult listOffsetsResult = adminClient.listOffsets(Collections.singletonMap(
                new TopicPartition("my-topic", 0),
                new ListOffsetsOptions().timestamp(OffsetAndMetadata.EARLIEST_TIMESTAMP)
        ));

        Map<TopicPartition, ListOffsetsResultInfo> offsets = listOffsetsResult.all().get();
        for (Map.Entry<TopicPartition, ListOffsetsResultInfo> entry : offsets.entrySet()) {
            System.out.println("Topic: " + entry.getKey().topic() + ", Partition: " + entry.getKey().partition() +
                    ", Offset: " + entry.getValue().offset());
        }

        adminClient.close();
    }
}