edit:
    display:
        "Ceny":  [_group_price_id]
    fields:
        group_price_id:  {name: Grupa cenowa, params: include_custom="---" include_blank=false, i18n: stGroupPriceBackend}
list:
  additional_filters: [group_price_id]
  fields:
    group_price_id:  {name: Grupa cenowa, i18n: stGroupPriceBackend}

export:
    fields:
        group_price:         {name: Grupa cenowa, class: stGroupPriceExport, method: getProduct}

import:
    fields:
        group_price:         {class: stGroupPriceExport, method: setProduct}