class BackupService {

  void validateRequestingSender(InternalDistributedMember sender) {
    // We need to watch for pure admin members that depart. this allMembershipListener set
    // looks like it should receive those events.
    Set allIds =
        cache.getDistributionManager().addAllMembershipListenerAndGetAllIds(membershipListener);
    if (!allIds.contains(sender)) {
      abortBackup();
      throw new IllegalStateException("The member requesting a backup has already departed");
    }
  }

  public  BackupService(InternalCache cache);

}