code: public Participant getLeader() throws Exception
      {
          Collection<String> participantNodes = mutex.getParticipantNodes();
          return getLeader(client, participantNodes);
      }
docs: <p>
  Return the id for the current leader. If for some reason there is no
  current leader, a dummy participant is returned.
  </p>
  <p>
  <p>
  <B>NOTE</B> - this method polls the ZK server. Therefore it can possibly
  return a value that does not match {@link #hasLeadership()} as hasLeadership
  uses a local field of the class.
  </p>
  
  @return leader
  @throws Exception ZK errors, interruptions, etc.