@Override
    public T add(K name, V value) {
        throw new UnsupportedOperationException("read only");
    }
@Test
    public void testAddStringValuesIterable() {
        assertThrows(UnsupportedOperationException.class, new Executable() {
            @Override
            public void execute() {
                HEADERS.add("name", Arrays.asList("value1", "value2"));
            }
        });
    }