docs: public Object[] toArray() {
          final ReentrantLock lock = this.lock;
          lock.lock();
          try {
              Object[] a = new Object[count];
              int k = 0;
              for (Node<E> p = first; p != null; p = p.next)
                  a[k++] = p.item;
              return a;
          } finally {
              lock.unlock();
          }
      }