code: public synchronized boolean allEvaluatorsAreClosed() {
      synchronized (this.evaluators) {
        for (final EvaluatorManager eval : this.evaluators.values()) {
          if (!eval.isClosed()) {
            return false;
          }
        }
      }
      return true;
    }
docs: Return true if <em>all</em> evaluators are in closed state
  (and their processing queues are empty).