code: void append(@NonNull Node<E> first, @NonNull Node<E> last) {
      for (;;) {
        Node<E> t = tail;
        if (casTail(t, last)) {
          t.lazySetNext(first);
          if (factory == OPTIMISIC) {
            return;
          }
          for (;;) {
            first.complete();
            if (first == last) {
              return;
            }
            Node<E> next = first.getNextRelaxed();
            if (next.value == null) {
              first.next = null; // reduce nepotism
            }
            first = next;
          }
        }
        Node<E> node = transferOrCombine(first, last);
        if (node == null) {
          first.await();
          return;
        } else if (node != first) {
          last = node;
        }
      }
    }
docs: Adds the linked list of nodes to the queue.