code: public void grantModerator(Resourcepart nickname) throws XMPPErrorException, NoResponseException, NotConnectedException, InterruptedException {
          changeRole(nickname, MUCRole.moderator, null);
      }
docs: Grants moderator privileges to a participant or visitor. Room administrators may grant
  moderator privileges. A moderator is allowed to kick users, grant and revoke voice, invite
  other users, modify room's subject plus all the partcipants privileges.
  
  @param nickname the nickname of the occupant to grant moderator privileges.
  @throws XMPPErrorException if an error occurs granting moderator privileges to a user.
  @throws NoResponseException if there was no response from the server.
  @throws NotConnectedException
  @throws InterruptedException