Entry<@Nullable K, V> entry = mapEntry(null, unmappedValue);
    assertTrue(entrySet.remove(entry));
    assertNull(map.get(null));
    assertFalse(map.containsKey(null));
  }

  public void testEntrySetRemoveNullKeyMissing() {
    Map<K, V> map;
    try {
      map = makeEitherMap();
    } catch (UnsupportedOperationException e) {
      return;
    }

    Set<Entry<K, V>> entrySet = map.entrySet();