已通过oAuth2（Grails/Java）身份验证的用户的Google Tasks服务对象

我正在尝试获取一个具有授权凭据的Google Tasks服务对象，以便我们可以为已经通过Google Apps Marketplace使用我们的Web应用程序注册并登录oAuth2的用户提取任务

不幸的是，我收到了401-授权-登录要求。谁能告诉我哪里出了问题

下面是我的GetTaskService方法的代码：

def httpTransport = new NetHttpTransport()
def jsonFactory = new JacksonFactory();

def clientId = GOOGLE_CLIENT_ID
def clientSecret = GOOGLE_SECRET
def applicationName = APPLICATION_NAME

def tokenResponse = (TokenResponse) googleAppsNewOAuthService.getGoogleResponse()
def credential = new GoogleCredential.Builder()
                                     .setJsonFactory(jsonFactory)
                                     .setTransport(httpTransport)
                                     .setClientSecrets(clientId, clientSecret)
                                     .build()
                                     .setFromTokenResponse(tokenResponse)

def service = new com.google.api.services.tasks.Tasks.Builder(httpTransport, jsonFactory, credential)
                                                     .setApplicationName(applicationName)
                                                     .build()
return service

googleAppsNewOAuthService.getGoogleResponse方法的代码：

public JSONElement getGoogleResponse() {
    def session = RequestContextHolder.currentRequestAttributes().getSession()
    Token googleAccessToken = (Token) session[oauthService.findSessionKeyForAccessToken('google')]

    log.info "Google Access Token: ${googleAccessToken.token}"

    if(googleAccessToken == null) {
        return null
    }

    def googleResource = oauthService.getGoogleResource(googleAccessToken, "https://www.googleapis.com/oauth2/v1/userinfo" )
    def googleResponse = JSON.parse(googleResource?.getBody())

    return googleResponse
}

。。。由此产生的GoogleJsonResponseException：

{
  "code" : 401,
  "errors" : [ {
    "domain" : "global",
    "location" : "Authorization",
    "locationType" : "header",
    "message" : "Login Required",
    "reason" : "required"
  } ],
  "message" : "Login Required"
}

at com.google.api.client.googleapis.json.GoogleJsonResponseException.from(GoogleJsonResponseException.java:145)