code: @Override
      protected <T> List<T> createListenerList(int sizeHint) {
          if (this.optimized) {
              return new CopyOnWriteArrayList<>();
          }
          return super.createListenerList(sizeHint);
      }
docs: {@inheritDoc}
  
  <p>
  After {@link #optimizeGet()} has been called, this method will return
  instances of {@link CopyOnWriteArrayList}.
  </p>