public static void main(String[] args) {
    List<GroupDetailDTO> list = new ArrayList<>();
    GroupDetailDTO dto1 = new GroupDetailDTO();
    dto1.setHeadsetId(1);
    dto1.setTime("2020-01-03");
    dto1.setActConcreteTime("a");
    dto1.setPlayed(1);
    list.add(dto1);

    GroupDetailDTO dto2 = new GroupDetailDTO();
    dto2.setHeadsetId(1);
    dto2.setTime("2020-01-01");
    dto2.setActConcreteTime("b");
    dto2.setPlayed(1);
    list.add(dto2);

    GroupDetailDTO dto3 = new GroupDetailDTO();
    dto3.setHeadsetId(1);
    dto3.setTime("2020-01-02");
    dto3.setActConcreteTime("c");
    dto3.setPlayed(1);
    list.add(dto3);

    GroupDetailDTO dto4 = new GroupDetailDTO();
    dto4.setHeadsetId(2);
    dto4.setTime("2020-01-01");
    dto4.setActConcreteTime("d");
    dto4.setPlayed(4);
    list.add(dto4);

    Map<GroupDetailDTO, Integer> collect = list.stream().collect(Collectors.groupingBy(o -> new GroupDetailDTO(o.getHeadsetId(), o.getTime()), TreeMap::new, Collectors.summingInt(o -> o.getPlayed())));
    collect.forEach((k, v) -> {
      System.out.println(k + "@@@" + v);
    });
  }

@Data
public class GroupDetailDTO implements Comparable<GroupDetailDTO> {
  private Integer headsetId;
  private String actConcreteTime;
  private String time;
  private Integer played;

  public GroupDetailDTO() {
  }

  public GroupDetailDTO(Integer headsetId, String time) {
    this.headsetId = headsetId;
    this.time = time;
  }

  @Override
  public int compareTo(GroupDetailDTO o) {
    String a = this.headsetId + "|" + this.getTime();
    String b = o.getHeadsetId() + "|" + o.getTime();
    return a.compareTo(b);
//    return this.getTime().compareTo(o.gtTime());
  }
}

return this.getTime().compareTo(o.getTime());