Review usage of get_multivalue and set_multivalue
The usage of such method should follow some rules in order to work correctly for #4080 (closed).
default_methods must use
patternas keyword argument and they must have an
on_change_method for the depending pattern (ex:
on_change_company) to set new default.
*_usedproperty may call
get_multivaluebut we must set the right context
get_context_formulaare exceptions that can use
There should be no other use cases.
set_multivalue should almost never be used (except to update the product cost) as multivalue is for referential document and they should be updated only by users.