@Override
    public Set<String> names() {
        return HeadersUtils.namesAsString(headers);
    }
@Test
    public void names() {
        HttpHeaders headers = new DefaultHttpHeaders(true)
                .add(ACCEPT, APPLICATION_JSON)
                .add(CONTENT_LENGTH, ZERO)
                .add(CONNECTION, CLOSE);
        assertFalse(headers.isEmpty());
        assertEquals(3, headers.size());
        Set<String> names = headers.names();
        assertEquals(3, names.size());
        assertTrue(names.contains(ACCEPT.toString()));
        assertTrue(names.contains(CONTENT_LENGTH.toString()));
        assertTrue(names.contains(CONNECTION.toString()));
    }