Multi threading initially supporting in Domain Object and Business Logic

In previous post i was make superficial review on DO and BL

DO should not, generally, support Multi threading initially.

BL should support initialy Multi threading in next case: static methods or static members

In case of static member always should support multi threading. It is shared entity by a-priory
In case of static method, if this method uses static member (which was described earlier) so it also should support multi threading.  If static method not uses any static members, it is should not support multi threading initially

Initially - i mean without considering customer. If customer wish DO supports multi threading -  this is the customers's concern.