sclass MapInConcept<K, V> implements Map<K, V> {
  Map<K, V> m;  // Backing Map
  Concept cc;

  *() {} // for persistence
  *(Map<K, V> *m, Concept *cc) {}

  public int size() {
      synchronized (this) {return m.size();}
  }
  public boolean isEmpty() {
      synchronized (this) {return m.isEmpty();}
  }
  public boolean containsKey(Object key) {
      synchronized (this) {return m.containsKey(key);}
  }
  public boolean containsValue(Object value) {
      synchronized (this) {return m.containsValue(value);}
  }
  public V get(Object key) {
      synchronized (this) {return m.get(key);}
  }

  public V put(K key, V value) {
      try { synchronized (this) {return m.put(key, value);} } finally { cc.change(); }
  }
  public V remove(Object key) {
      try { synchronized (this) {return m.remove(key);} } finally { cc.change(); }
  }
  public void putAll(Map<? extends K, ? extends V> map) {
      synchronized (this) {m.putAll(map);} cc.change();
  }
  public void clear() {
      synchronized (this) {m.clear();} cc.change();
  }

  private transient Set<K> keySet;
  private transient Set<Map.Entry<K,V>> entrySet;
  private transient Collection<V> values;

  public Set<K> keySet() {
      synchronized (this) {
          if (keySet==null)
              keySet = new SynchronizedSet(m.keySet(), this);
          return keySet;
      }
  }

  public Set<Map.Entry<K,V>> entrySet() {
      synchronized (this) {
          if (entrySet==null)
              entrySet = new SynchronizedSet(m.entrySet(), this);
          return entrySet;
      }
  }

  public Collection<V> values() {
      synchronized (this) {
          if (values==null)
              values = new SynchronizedCollection(m.values(), this);
          return values;
      }
  }

  public boolean equals(Object o) {
      if (this == o)
          return true;
      synchronized (this) {return m.equals(o);} // TODO: deadlock?
  }
  public int hashCode() {
      synchronized (this) {return m.hashCode();}
  }
  public String toString() {
      synchronized (this) {return m.toString();}
  }

  // 1.8 stuff omitted
  
  Map<K, V> unwrap() { ret m; }
}

Began life as a copy of #1009405