future1.set(1L);
    future1 = null;
    future2.set(2L);
    future2 = null;

    /*
     * Futures should be collected even if combiner never runs. This is kind of a silly test, since
     * the combiner is almost certain to hold its own reference to the futures, and a real app would
     * hold a reference to the executor and thus to the combiner. What we really care about is that

    future1.set(1L);
    future1 = null;
    future2.set(2L);
    future2 = null;

    /*
     * Futures should be collected even if combiner never runs. This is kind of a silly test, since
     * the combiner is almost certain to hold its own reference to the futures, and a real app would
     * hold a reference to the executor and thus to the combiner. What we really care about is that

   * created arrays to have a {@code @Nullable} element type even when they're created directly with
   * {@code new ImmutableMapEntry[...]}, so it seems silly to insist on that only here.
   */
  @SuppressWarnings("unchecked") // Safe as long as the javadocs are followed
  static <K, V> ImmutableMapEntry<K, V>[] createEntryArray(int size) {