Updates an existing company user, including submitted Address and UserEmployment child objects (but not child objects of UserEmployments). Notice that other child objects cannot be added and removed this way, only modified. Provide null values (not empty lists) to leave child objects unmodified. Note that the convenience fields UserLanguageId and UserIdentityNumber, which really belong to the User object in the hiarchy, may be updated this way. Finally, notice that users with the Employee role can only update their own CompanyUsers, and NOT the attached UserEmployment objects.