Properties implements Serializable { @Override public String toString() { return properties.toString(); }  void put(Property key, PropertyValue propertyValue); PropertyValue get(final Property key); String getStringValue(final Property key); Set<Map.Entry<Property, PropertyValue>> entrySet(); int getSize(); @Override String toString();  }
@Test public void testToString() throws Exception { final Properties props = new Properties(); assertEquals("{}", props.toString()); props.put(new Property("key"), new PropertyValue("value")); assertEquals("{key=value}", props.toString()); }