// empty
assertTrue(properties.isEmpty());
assertEquals(0, properties.size());
assertTrue(properties.keySet().isEmpty());
assertEquals(0, properties.keySet().size());
assertTrue(properties.values().isEmpty());
assertEquals(0, properties.values().size());
assertTrue(properties.entrySet().isEmpty());
assertEquals(0, properties.entrySet().size());
assertFalse(properties.keys().hasMoreElements());
assertFalse(properties.propertyNames().hasMoreElements());