JSON implements Serializable { public static JSON empty() { return EMPTY_JSON; } private  JSON(Map<String, Object> data); private  JSON(String path, Map<String, Object> data); static JSON parse(InputStream in); static JSON parse(String json); static JSON empty(); Set<String> keySet(); boolean contains(String key); Value get(String key); @Override String toString(); Map<String,Object> toMap();  }
@Test public void testEmpty() { JSON empty = JSON.empty(); assertThat(empty.toString(), is("{}")); assertThat(empty.toMap().keySet(), is(empty())); }