xmlrpclib can not dump defaultdict
From http://www.tryton.org/~irclog/2017-11-15.log.html#t2017-11-15%2020:38
The xmlrpclib can not dump defaultdict, so RPC method like on_change should not return such type.
This instance will be upgraded to Heptapod 1.3.3 (GitLab 16.9.6) on 2023-04-25 at 18:00 UTC+2
From http://www.tryton.org/~irclog/2017-11-15.log.html#t2017-11-15%2020:38
The xmlrpclib can not dump defaultdict, so RPC method like on_change should not return such type.