how do i use XDefault with enum type?

how do i use XDefault with enum type? I tried to enter the index, but it didn't work.

EInvalidDefaultvalue: Cannot define action "ListaItemMat": Invalid default value for param "Rotina"

[Enumeration(TEnumMappingType.emInteger)]
TRotina = (rtOrcamento, rtVenda, rtOutrosMovimentos, rtMovimentacaoInterna, rtNull);

[HttpGet]
function ListaItemMat(CentresAdmId: Int64; [XDefault(4)]Rotina: TRotina): TList;

That is not currently possible, to define default values for enumerated types. If you need it please file a feature request at #business:biz-feature-requests.