I suggest you to specify that URL in your code like the following snippet:
CalendarService myService = new CalendarService("CalendarService");
myService.setUserCredentials("example@gmail.com", "yourPassword");
URL feedUrl = new URL("http://www.google.com/calendar/feeds/default/allcalendars/full");
CalendarFeed resultFeed = myService.getFeed(feedUrl, CalendarFeed.class);
System.out.println("Your calendars:");
for (int i = 0; i < resultFeed.getEntries().size(); i++) {
CalendarEntry entry = resultFeed.getEntries().get(i);
System.out.println(" " + entry.getTitle().getPlainText());
}
CalendarEntry instances will store every calendars (primary, secondary,imported calendars) retrieved by the specified URL.