LinkedProperties extends Properties { @Override public synchronized Enumeration<Object> elements() { throw new UnsupportedOperationException( "Please use keySet() or entrySet() instead of Enumeration."); }  @Override synchronized Object put(Object key, Object value); @Override synchronized boolean contains(Object value); @Override boolean containsValue(Object value); @Override synchronized Enumeration<Object> elements(); @Override Set<Map.Entry<Object, Object>> entrySet(); @Override synchronized void clear(); @Override synchronized boolean containsKey(Object key);  }
@Test(expected = UnsupportedOperationException.class) public void elementsTest() { linkedProperties.elements(); }