assertThrows(
          UnsupportedOperationException.class, () -> cache.asMap().keySet().addAll(asList(1, 2)));
    }
  }


  public void testKeySet_clear() {
    for (LoadingCache<Object, Object> cache : caches()) {
      warmUp(cache, 0, 100);

      Set<Object> keys = cache.asMap().keySet();
      keys.clear();
      checkEmpty(keys);