code: public T friends_get(Long friendListId)
      throws FacebookException, IOException {                                                                                                                
      FacebookMethod method = FacebookMethod.FRIENDS_GET;
      Collection<Pair<String, CharSequence>> params =
        new ArrayList<Pair<String, CharSequence>>(method.numParams());
      if (null != friendListId) {
        if (0L >= friendListId) {
          throw new IllegalArgumentException("given invalid friendListId " + friendListId.toString());
        }
        params.add(new Pair<String, CharSequence>("flid", friendListId.toString()));
      }
      
      return this.callMethod(method, params);
    }
docs: Retrieves the friends of the currently logged in user that
  are members of the friends list with ID <code>friendListId</code>.
  @param friendListId the friend list for which friends should be fetched.
  if <code>null</code>, all friends will be retrieved.
  @return T of friends
  @see <a href="http://wiki.developers.facebook.com/index.php/Friends.get">
  Developers Wiki: Friends.get</a>