@Override
  public Writable put(K key, Writable value) {
    addToMap(key.getClass());
    addToMap(value.getClass());
    return instance.put(key, value);
  }
@Test
  @SuppressWarnings("deprecation")
  public void testForeignClass() {
    SortedMapWritable<Text> inMap = new SortedMapWritable<Text>();
    inMap.put(new Text("key"), new UTF8("value"));
    inMap.put(new Text("key2"), new UTF8("value2"));
    SortedMapWritable<Text> outMap = new SortedMapWritable<Text>(inMap);
    SortedMapWritable<Text> copyOfCopy = new SortedMapWritable<Text>(outMap);
    assertEquals(1, copyOfCopy.getNewClasses());
  }