boolean done = doneSignal.await(1, TimeUnit.SECONDS);
    if (!done) {
      StringBuilder builder = new StringBuilder();
      for (StackTraceElement trace : thread.getStackTrace()) {
        builder.append("\tat ").append(trace).append('\n');
      }
      fail(builder.toString());
    }
  }

  /**
   * Returns an iterable containing all combinations of maximumSize, expireAfterAccess/Write,

    boolean done = doneSignal.await(1, TimeUnit.SECONDS);
    if (!done) {
      StringBuilder builder = new StringBuilder();
      for (StackTraceElement trace : thread.getStackTrace()) {
        builder.append("\tat ").append(trace).append('\n');
      }
      fail(builder.toString());
    }
  }

  /**
   * Returns an iterable containing all combinations of maximumSize, expireAfterAccess/Write,