我正在嘗試將 JSON 文件反序列化為 POJO 對象，但出現錯誤。JSON 文件看起來像 (NotificationPOST.json)  {   "endDate":"2018-12-27",   "malfunctionStartDate":"2018-11-20T22:22:22",   "malfunctionEndDate":"2018-11-21T12:34:46"   }POJO類有 @DateFormat(field = "Start Date", groups = Order.Level2.class)    @JsonSerialize(using = DateSerializer.class)    private DateTime startDate;    @DateFormat(field = "End Date", groups = Order.Level2.class)    @JsonSerialize(using = DateSerializer.class)    private DateTime endDate;自定義 DateSerializer 類import com.fasterxml.jackson.core.JsonGenerator;import com.fasterxml.jackson.core.JsonProcessingException;import com.fasterxml.jackson.databind.JsonSerializer;import com.fasterxml.jackson.databind.SerializerProvider;import java.io.IOException;import org.joda.time.DateTime;import org.joda.time.format.DateTimeFormat;import org.joda.time.format.DateTimeFormatter;public class DateSerializer extends JsonSerializer<DateTime> {    private static DateTimeFormatter formatter = DateTimeFormat.forPattern("yyyy-MM-dd");    public DateSerializer() {    }    public void serialize(DateTime value, JsonGenerator gen, SerializerProvider serializers) throws IOException, JsonProcessingException {        gen.writeString(formatter.print(value));    }}我試圖運行的測試類@BeforeClass    public static void init() {        notificationPOST = new File("src/test/resources/json/NotificationPOST.json");    }@Testpublic void notificationPayloadToEntityTest () throws IOException {private ObjectMapper objectMapper = new ObjectMapper();    NotificationPOST post = objectMapper.readValue(notificationPOST, NotificationPOST.class);}