Group calendar creation in Google Calendar API

Question

So basically my Java app is creating one or few Google calendars for each of our Google domain users.

To overcome calendar creation limits (25 cals per few hours or so) I implemented Service Account that is impersonating each of said users. Said service account has API access defined in admin console.

I have created all of those calendars successfully by setting:

.setServiceAccountUser("username@ourdomain.com").

But now I need to create a calendar for each group. If I try to impersonate a group user (.setServiceAccountUser("groupname@ourdomain.com")), I get such error:

400 Bad Request
{
  "error" : "access_denied",
  "error_description" : "Requested scopes not allowed:
   https://www.googleapis.com/auth/calendar 
   https://www.googleapis.com/auth/calendar.readonly"
}

Relevant code:

private static HttpTransport httpTransport;

private static final String SERVICE_ACCOUNT_EMAIL = "serviceaccountetcetera@developer.gserviceaccount.com";
private static final String SERVICE_ACCOUNT_PKCS12_FILE_PATH = "path\to.p12";    

JacksonFactory jsonFactory = new JacksonFactory();
GoogleCredential credential = new GoogleCredential.Builder()
 .setTransport(httpTransport)
 .setJsonFactory(jsonFactory)
 .setServiceAccountId(SERVICE_ACCOUNT_EMAIL)
 .setServiceAccountScopes(CalendarScopes.all())
 .setServiceAccountPrivateKeyFromP12File(new java.io.File(
  SERVICE_ACCOUNT_PKCS12_FILE_PATH))
 .setServiceAccountUser("groupname@ourdomain.com")
 .build();

client = new com.google.api.services.calendar.Calendar.Builder(httpTransport, 
 JSON_FACTORY, credential).setApplicationName(
 APPLICATION_NAME).build();

Calendar entry = new Calendar();
entry.setSummary("summary");

Calendar result = client.calendars().insert(entry).execute();

Why can't I impersonate group username to create a group calendar? How do I create a few hundred group calendars in some other way?

Answer 1

Google support says that it is not possible to impersonate group user.

I have to create calendar by impersonating some group user and share it with a group.