// ----------------------------------------------------------
  private NSArray<Submission> extractSubmissions(NSArray<UserSubmissionPair> userSubs) {
    NSMutableArray<Submission> submissions = new NSMutableArray<Submission>();

    for (UserSubmissionPair pair : userSubs) {
      if (pair.userHasSubmission()) {
        submissions.addObject(pair.submission());
      }
    }

    return submissions;
  }