public synchronized Set<K> keySet() {Set<K> ks = keySet;return (ks != null) ? ks : (keySet = new KeySet());}

public virtual java.util.Set<K> keySet(){lock (this){java.util.Set<K> ks = _keySet;return (ks != null) ? ks : (_keySet = new java.util.Hashtable<K, V>.KeySet(this));}}
