private void checkWasNotAddedAlreadyAsChild(@NotNull ObjectNode childNode, @NotNull ObjectNode parentNode) throws IncorrectOperationException {
    for (ObjectNode node = childNode; node != myRootNode && node != null; node = myObject2ParentNode.get(node.getObject())) {
      if (node == parentNode) {
        throw new IncorrectOperationException("'"+childNode.getObject() + "' was already added as a child of '" + parentNode.getObject()+"'");
      }
    }
  }
private void checkWasNotAddedAlreadyAsChild(@NotNull ObjectNode childNode, @NotNull ObjectNode parentNode)