### Question:
HttpHeaders { public void add(String name, String value) { List<String> values = headers.get(name); if (values == null) { values = new ArrayList<>(1); headers.put(name, values); } values.add(value); } HttpHeaders(int size);  HttpHeaders(Map<String, List<String>> headers); String get(String name); List<String> getValues(String name); void set(String name, String value); void add(String name, String value); List<String> names(); Map<String, List<String>> headers(); static HttpHeaders defaultHeaders();  }### Answer:
@Test public void testAdd() { HttpHeaders headers = new HttpHeaders(2); headers.set("Connection", "Keep-Alive"); headers.add("Connection", "close"); Assert.assertEquals("Keep-Alive", headers.get("Connection")); Assert.assertEquals(Arrays.asList("Keep-Alive", "close"), headers.getValues("Connection")); }