* seenExceptions to its exception
     *
     * Thread2: calls setException(), which returns false, CASes seenExceptions to its exception,
     * and wrongly believes that its exception is new (leading it to logging it when it shouldn't)
     *
     * Our solution is for threads to CAS seenExceptions from null to a Set populated with _the

  private @Nullable Set<Throwable> seenExceptions = null;
  private int remaining;

  AggregateFutureState(int remainingFutures) {
    this.remaining = remainingFutures;
  }

  final Set<Throwable> getOrInitSeenExceptions() {
    if (seenExceptions == null) {
      seenExceptions = newHashSet();
      addInitialException(seenExceptions);
    }
    return seenExceptions;
  }

     * seenExceptions to its exception
     *
     * Thread2: calls setException(), which returns false, CASes seenExceptions to its exception,
     * and wrongly believes that its exception is new (leading it to logging it when it shouldn't)
     *
     * Our solution is for threads to CAS seenExceptions from null to a Set populated with _the