if (listener != null) {
            AtomicReference<Model> m = new AtomicReference<>(model);

            ModelBuildingEvent event = new DefaultModelBuildingEvent(model, m::set, request, problems);

            catapult.accept(listener, event);

            return m.get();
        }

        return model;
    }

      ATOMIC_HELPER.putNext(this, next);
    }

    void unpark() {
      // This is racy with removeWaiter. The consequence of the race is that we may spuriously call
      // unpark even though the thread has already removed itself from the list. But even if we did
      // use a CAS, that race would still exist (it would just be ever so slightly smaller).
      Thread w = thread;
      if (w != null) {
        thread = null;

   * resulting segment inside the cache <i>independently</i> limits its own size to approximately
   * {@code maximumSize / concurrencyLevel}.
   *
   * <p>When eviction is necessary, the cache evicts entries that are less likely to be used again.
   * For example, the cache may evict an entry because it hasn't been used recently or very often.
   *