Objectify and strange errors with GWT serializations

OK, so it turns out Objectify returns non-serializable lists when using the list() method. Using the following method :

ofy.load().type(Plant.class).list();

And directly returning the value to GWT client side throws a cryptic serialization exception, where the class that raises the problem is called Proxy$XX where XX are digits.

That problem is going to be fixed in GWT next version, but meanwhile we have to use the workaround provided in the bug report.