field_order

If the submitted parts should be joined in an order different than that of the order of the fields, you must provide an arrayref containing the names, in the order they should be joined.

    ---
    element:
      - type: Multi
        name: address

        elements:
          - name: street
          - name: number

        filter:
          - type: CompoundJoin
            field_order:
              - number
              - street