@Override
                  public Iterator<String> iterator() {
                    return singleton("a").iterator();
                  }
                }));
  }

  public void testIsEmpty_map() {
    Map<Object, Object> map = new HashMap<>();
    assertEmpty(map);

    map.put("a", "b");
    assertThrows(AssertionFailedError.class, () -> assertEmpty(map));
  }

                  @Override
                  public Iterator<String> iterator() {
                    return singleton("a").iterator();
                  }
                }));
  }

  public void testIsEmpty_map() {
    Map<Object, Object> map = new HashMap<>();
    assertEmpty(map);

    map.put("a", "b");
    assertThrows(AssertionFailedError.class, () -> assertEmpty(map));
  }