AssignedBy for codes and identifiers, e.g. for transport units

[larsolofsson]

Currently in 4.0.0 for transport units, detailCode is assigned by Supplier and identifier is assignedBy LogisticsSupplier or Supplier.
Currently no agency is specified, e.g. for identifiers of railcars.
How to handle this in 5.0.0?

Currently schemas in 4.00 for example for transport units.

 detailCode:
 type: object
 unevaluatedProperties: false
 required:
 - value
 - assignedBy
 properties:
 value:
 type: string
 minLength: 1
 assignedBy:
 type: string
 enum:
 - Supplier

 identifier:
 type: object
 unevaluatedProperties: false
 required:
 - type
 - value
 properties:
 type:
 type: string
 enum:
 - ContainerID
 - CassetteID
 - ISO6346ContainerNumber
 # Don't use `assignedBy` with ISO6346ContainerNumber!
 - LicencePlateNumber
 - RailCarID
 - RFTagSerialNumber
 - SealNumber
 - TrailerID
 - VesselUnitID
 value:
 type: string
 minLength: 1
 assignedBy:
 type: string
 enum:
 - LogisticsSupplier
 - Supplier
 countryCode:
 type: string
 minLength: 2
 maxLength: 2

[larsolofsson]

See also issue #321

[larsolofsson]

So far, Codes, location identifiers and party identifiers are assigned by Supplier.
The construct for detailCode could be replaced by a simple property similar to identifiers for location and party.
There many properties code: that are assigned by Supplier

detailCodeBySupplier:
 type: string
 minLength: 1
 description: The detailCode defined by the _Supplier_.