OK. If understand correctly, changing line 47 from
java.util.logging.LogManager.getLogManager()
to
{{ java.util.logging.Logger.getLogger("");}}
would work on GAE (as well as other platforms). Just as important, both forms would have the JUL-initializing effect.

Osvaldo Pinali Doederlein Can you please check that the latter form works on GAE? (From your explanations, I am fairly confident that the latter form would work just fine.)