An already registered connector was registered again

I am getting this warning and I can’t understand how to avoid it. My suspect is that Vaadin 7 does not allow to assemble bottom up. Here is what I do: I create, say, an horizontal layout and add it some buttons. Then I add this layout to a grid that has ALREADY been added to the UI. At this point I get this message for all components contained in the layout that was added.

Googling for this message, I find many questions, but no answers. Do anybody knows what exactly ti means and how can be avoided?


Let me respond to myself.

The problem was an attach listener. I was changing the content of the component inside the attachment listener. The component contained a layout that could be vertical or horizontal, attaching it I was removing the existent component (if any) and reattaching all its content to the new layout.