* SuppressWarnings("unchecked")
   * Set<String> badStrings = (Set) Sets.intersection(
   *     aFewBadObjects, manyBadStrings);
   * }</pre>
   *
   * <p>This is unfortunate, but should come up only very rarely.
   */
  public static <E extends @Nullable Object> SetView<E> intersection(
      final Set<E> set1, final Set<?> set2) {
    checkNotNull(set1, "set1");
    checkNotNull(set2, "set2");

 *             return createExpensiveGraph(key);
 *           }
 *         });
 * }</pre>
 *
 * <p>Or equivalently,
 *
 * <pre>{@code
 * // In real life this would come from a command-line flag or config file
 * String spec = "maximumSize=10000,expireAfterWrite=10m";
 *
 * LoadingCache<Key, Graph> graphs = CacheBuilder.from(spec)
 *     .removalListener(MY_LISTENER)
 *     .build(

   * listeners for future n may complete before some for future n-1.) However, it is possible, if
   * one input completes with result X and another later with result Y, for Y to come before X in
   * the output future list. (Such races are impossible to solve without global synchronization of
   * all future completions. And they should have little practical impact.)
   *