### Question:
ParenthesisSerializer { public static <T> String serialize(final Collection<T> collection) { if (collection.isEmpty()) { return ""; } final String joined = collection.stream() .map(Object::toString) .collect(Collectors.joining("),(")); return '(' + joined + ')'; }  static String serialize(final Collection<T> collection); static List<String> deserialize(final String value);  }### Answer:
@Test public void serialize() { assertEquals("", ParenthesisSerializer.serialize(Collections.emptyList())); assertEquals("(a)", ParenthesisSerializer.serialize(Arrays.asList("a"))); assertEquals("(a),(b),(c)", ParenthesisSerializer.serialize(Arrays.asList("a", "b", "c"))); }