code: public ItemImpl update(ItemState itemState, boolean pool) throws RepositoryException
     {
        if (itemState.isDeleted())
        {
           throw new RepositoryException("Illegal state DELETED. Use delete(...) method");
        }
  
        changesLog.add(itemState);
  
        return readItem(itemState.getData(), null, pool, false);
     }
docs: Updates (adds or modifies) item state in the session transient storage.
  
  @param itemState
  - the state
  @param pool
  - if true Manager force pooling this State so next calling will returna the same
  object Common rule: use pool = true if the Item supposed to be returned by JCR API
  (Node.addNode(), Node.setProperty() for ex) (NOTE: independently of pooling the
  Manager always return actual Item state)
  @return
  @throws RepositoryException