These documents were probably edited before they had correct property
sheets, because they had local properties as incorrect type, as reported
by PropertyTypeValidity:

    <ERP5Type.ConsistencyMessage for PropertyTypeValidity type_check on portal_gadgets/erp5_persons (message: Attribute gadget_type should be of type lines but is of type <type 'str'>)>
    <ERP5Type.ConsistencyMessage for PropertyTypeValidity type_check on portal_gadgets/erp5_gadget_new_sale_opportunity (message: Attribute gadget_type should be of type lines but is of type <type 'str'>)>
    <ERP5Type.ConsistencyMessage for PropertyTypeValidity type_check on portal_gadgets/erp5_gadget_contact_person (message: Attribute gadget_type should be of type lines but is of type <type 'str'>)>