code: public static boolean isSingleEpsilonOnly(Set<Transition<NFAState>> set)
      {
          if (set.size() != 1)
          {
              return false;
          }
          for (Transition<NFAState> tr : set)
          {
              if (tr.isEpsilon())
              {
                  return true;
              }
          }
          return false;
      }
docs: Returns true if set only has one epsilon transition.
  @param set
  @return