code: private void checkBuddyManagerIsActive(BuddyListManager buddyListManager, User sfsOwner) {
          if (!buddyListManager.isActive()) {
              throw new IllegalStateException(
                      String.format("BuddyList operation failure. BuddyListManager is not active. Zone: %s, Sender: %s", new Object[] { sfsOwner.getZone(), sfsOwner }));
            }
      }
docs: Check whether buddy manager is active
  
  @param buddyListManager manager object
  @param sfsOwner buddy's owner