如何使用OAuth 2.0访问Google日历(服务模型)?

我正在尝试让Groovy/Grails应用程序使用服务模型从Java与GoogleCalendarAPI对话。现在,我会很高兴看到一个简单的日历列表。不管我做什么,我最终都是:

URI: /test
Class: com.google.api.client.auth.oauth2.TokenResponseException
Message: 400 Bad Request { "error" : "invalid_grant" }

同一用户“googleaccounts@quirk.biz“同时拥有日历和API控制台应用程序。代码如下:

package quirkplanner

import com.google.api.client.googleapis.auth.oauth2.GoogleCredential;
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport
import com.google.api.client.http.HttpTransport
import com.google.api.client.json.JsonFactory
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.services.calendar.Calendar
import com.google.api.services.calendar.model.*;

class TestController {

    def servletContext

    private static final HttpTransport HTTP_TRANSPORT = GoogleNetHttpTransport.newTrustedTransport();
    private static final JsonFactory JSON_FACTORY = new JacksonFactory();

    private static final String SERVICE_EMAIL = "12345678901234-abcdefabcdef@developer.gserviceaccount.com";
    private static final String CLIENT_ID = "12345678901234.apps.googleusercontent.com";
    private static final String PATH_TO_CERTIFICATE = "/WEB-INF/abcdefabcdef-privatekey.p12";
    private static final String SERVICE_ACCOUNT_USER="my-google-admin-user@quirk.biz";

    def index() {

        GoogleCredential credential = new GoogleCredential.Builder().setTransport(HTTP_TRANSPORT)
            .setJsonFactory(JSON_FACTORY)
            .setServiceAccountId(SERVICE_EMAIL)
            .setServiceAccountScopes(Collections.singleton("https://www.googleapis.com/auth/calendar"))
            .setServiceAccountPrivateKeyFromP12File(new File(servletContext.getRealPath(PATH_TO_CERTIFICATE)))
            .setServiceAccountUser(SERVICE_ACCOUNT_USER)
            .build();

        Calendar service3 = new Calendar(HTTP_TRANSPORT, JSON_FACTORY, credential);
        com.google.api.services.calendar.model.Calendar calendar = service3.calendars().get("primary").execute();

        render("ok")
    }
}

BuildConfig.groovy依赖项包括:

    compile 'com.google.api-client:google-api-client:1.18.0-rc'
    compile 'com.google.http-client:google-http-client-jackson2:1.18.0-rc'

我还有一个我正在使用的JAR的列表。列表不完整,因此存在BuildConfig依赖项。理想情况下,我真的应该选择其中一个。。。