throw new Error ("not implemented");
int i = keystrokes.size (); Iterator iter = keystrokes.iterator ();  while (--i >= 0) { Object o = iter.next (); if (!(o instanceof AWTKeyStroke) || sa.contains (o) || sb.contains (o) || sc.contains (o) || ((AWTKeyStroke) o).keyCode == KeyEvent.VK_UNDEFINED) throw new IllegalArgumentException (); }  if (focusTraversalKeys == null) focusTraversalKeys = new Set[3];  keystrokes = Collections.unmodifiableSet (new HashSet (keystrokes)); firePropertyChange (name, focusTraversalKeys[id], keystrokes);  focusTraversalKeys[id] = keystrokes;
  public void setFocusTraversalKeys(int id, Set keystrokes)  {    if (id != KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS &&        id != KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS &&        id != KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS &&        id != KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS)      throw new IllegalArgumentException ();    if (keystrokes == null)      throw new IllegalArgumentException ();    throw new Error ("not implemented");  }