Google Admin API を使用して、ドメインのユーザーを取得して更新しようとしています。
  private static final JsonFactory JSON_FACTORY = JacksonFactory.getDefaultInstance();
  private static final List<String> SCOPES = Arrays.asList(
      "https://www.googleapis.com/auth/admin.directory.user",
      "https://www.googleapis.com/auth/admin.directory.user.readonly");
  public static void main(String[] args) {
    try {
      HttpTransport httpTransport = new NetHttpTransport();
      GoogleCredential credential =
          new GoogleCredential.Builder()
              .setTransport(httpTransport)
              .setJsonFactory(JSON_FACTORY)
              .setServiceAccountId(
                  "xxxxx-yyyyy@developer.gserviceaccount.com")
              .setServiceAccountUser("superadmin@mydomain.com")
              .setServiceAccountScopes(SCOPES)
              .setServiceAccountPrivateKeyFromP12File(
                  new File("C:\\privatekey.p12")).build();
      Directory admin =
          new Directory.Builder(httpTransport, JSON_FACTORY, credential)
              .setApplicationName("User Sync Service")
              .setHttpRequestInitializer(credential).build();
      Directory.Users.List list = admin.users().list();
      Users users = list.execute();
      System.out.println("************");
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
Google コンソールから
 

- セキュリティ パネルから API アクセスが有効になっている
- ServiceAccountUser はスーパー管理者です。
しかし、私はまだこのエラーが発生しています
com.google.api.client.auth.oauth2.TokenResponseException: 400 Bad Request
{
  "error" : "access_denied"
}
    at com.google.api.client.auth.oauth2.TokenResponseException.from(TokenResponseException.java:105)
    at com.google.api.client.auth.oauth2.TokenRequest.executeUnparsed(TokenRequest.java:287)
    at com.google.api.client.auth.oauth2.TokenRequest.execute(TokenRequest.java:307)
    at com.google.api.client.googleapis.auth.oauth2.GoogleCredential.executeRefreshToken(GoogleCredential.java:269)
    at com.google.api.client.auth.oauth2.Credential.refreshToken(Credential.java:489)
    at com.google.api.client.auth.oauth2.Credential.intercept(Credential.java:217)
    at com.google.api.client.http.HttpRequest.execute(HttpRequest.java:858)
    at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:410)
    at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:343)
    at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.execute(AbstractGoogleClientRequest.java:460)
更新: ManageOath のスクリーンショット
