ImmutableList<ListenableFuture<Long>> delegates =
        inCompletionOrder(ImmutableList.<ListenableFuture<Long>>of(future1, future2, future3));

    future1.set(1L);
    // Cannot cancel a complete delegate
    assertFalse(delegates.get(0).cancel(true));
    // Cancel the delegate before the input future is done
    assertTrue(delegates.get(1).cancel(true));

    ImmutableList<ListenableFuture<Long>> delegates =
        inCompletionOrder(ImmutableList.<ListenableFuture<Long>>of(future1, future2, future3));

    future1.set(1L);
    // Cannot cancel a complete delegate
    assertFalse(delegates.get(0).cancel(true));
    // Cancel the delegate before the input future is done
    assertTrue(delegates.get(1).cancel(true));

          return entryIterator();
        }
      };
    }

    @Override
    public void clear() {
      Iterators.clear(entryIterator());
    }
  }

  /**
   * Delegates to {@link Map#get}. Returns {@code null} on {@code ClassCastException} and {@code
   * NullPointerException}.
   */
  @CheckForNull