我正在尝试连接到google日历api。我已经遵循了googlecalendarquickstart中的步骤
{“error”：“invalid\u grant”，“error\u description”：“bad request”}
你能告诉我怎么调试这个吗？不幸的是，错误消息没有帮助，我已经尝试了所有我能找到的关于堆栈溢出或其他地方的这个特定错误的信息
每次我为不同的凭据获得相同的访问令牌时：
访问令牌：{user=class{accesstoken=null，refreshttoken=“”expirationtimemillishes=null}}
代码：

public class CalendarServiceImpl implements CalendarService {

    public static final String APPLICATION_NAME = "GoogleCalenderApi";
    public static final JsonFactory JSON_FACTORY = JacksonFactory.getDefaultInstance();
    public static final String TOKENS_DIRECTORY_PATH = "/data.json";
    public static final List<String> SCOPES = Collections.singletonList(CalendarScopes.CALENDAR);
    public static final String CREDENTIALS_FILE_PATH = "/data.json";

    public Credential getCredentials(final NetHttpTransport HTTP_TRANSPORT, HttpServletRequest request)
            throws IOException {

        InputStream in = CalendarServiceImpl.class.getResourceAsStream(CREDENTIALS_FILE_PATH);

        if (in == null) {
            log.info("Resource not found: " + CREDENTIALS_FILE_PATH);
            throw new FileNotFoundException("Resource not found: " + CREDENTIALS_FILE_PATH);
        }

        GoogleClientSecrets clientSecrets = GoogleClientSecrets.load(JSON_FACTORY, new InputStreamReader(in));
        GoogleAuthorizationCodeFlow flow = new GoogleAuthorizationCodeFlow.Builder(HTTP_TRANSPORT, JSON_FACTORY,
                clientSecrets, SCOPES)
                        .setDataStoreFactory(new FileDataStoreFactory(new java.io.File(TOKENS_DIRECTORY_PATH)))
                        .setAccessType("offline")
                        .build();

        System.out.println("Access token: " + flow.getCredentialDataStore());

        LocalServerReceiver receiver = new LocalServerReceiver.Builder().setPort(80)
                .build();

        return new AuthorizationCodeInstalledApp(flow, receiver).authorize("user");
    }

    public void createCalendarEvent(String candidateMailId, String companyEmailId, DateTime fromTime, DateTime toTime,
            String summary, String description, HttpServletRequest request)
            throws GeneralSecurityException, IOException {
        final NetHttpTransport HTTP_TRANSPORT = GoogleNetHttpTransport.newTrustedTransport();

        Event event = new Event().setSummary(summary).setLocation("Test").setDescription(description);

        EventDateTime start = new EventDateTime().setDateTime(fromTime).setTimeZone("Asia/Kolkata");
        event.setStart(start);

        EventDateTime end = new EventDateTime().setDateTime(toTime).setTimeZone("Asia/Kolkata");
        event.setEnd(end);

        String[] recurrence = new String[] { "RRULE:FREQ=DAILY" };
        event.setRecurrence(Arrays.asList(recurrence));

        EventAttendee[] attendees = new EventAttendee[] { new EventAttendee().setEmail(candidateMailId),
                new EventAttendee().setEmail(companyEmailId) };
        event.setAttendees(Arrays.asList(attendees));

        EventReminder[] reminderOverrides = new EventReminder[] { new EventReminder().setMethod("email").setMinutes(10),
                new EventReminder().setMethod("popup").setMinutes(10), };
        Event.Reminders reminders = new Event.Reminders().setUseDefault(false)
                .setOverrides(Arrays.asList(reminderOverrides));
        event.setReminders(reminders);

        // Build service account credential.
        Credential credential = getCredentials(HTTP_TRANSPORT, request);
        log.info("got  credential:" + event);

        Calendar service = new Calendar.Builder(HTTP_TRANSPORT, JSON_FACTORY, credential)
                .setApplicationName(APPLICATION_NAME).build();

        String calendarId = "primary";
        try {
            System.out.printf("Event started" + event);
            event = service.events().insert(calendarId, event).setSendUpdates("all").execute();
        } catch (IOException e) {
            log.info("event  IOException:" + e);
            e.getMessage();
        }
        log.info("Event created:" + event.getHtmlLink());

    }

}