code: private static Transition getTransitionSingleGroup(Collection<String> groups)
      {
          final Iterator<String> iterator = groups.iterator();
          final String group = iterator.next();
  
          return new Transition(TransitionType.CENTER, group, group);
      }
docs: Get the tile transition with one group only.
  
  @param groups The groups (must contain one group).
  @return The tile transition.