How to map fields to a set

[ArkasDev]

I want to use the Orika mapper to map attributes of a class into a set. Previously I implemented it with a list, however I want to get rid of the indices in the Orika factories, because the order of the elements is not important.

For the list implementation, the declarative mapping configuration in the Orika factories worked quite well. When I changed everything to Set, Orika's field mapping no longer works. Does anyone know why? Do I have a wrong declaration of the field mapping?

Set<AssetAdministrationShell> administrationShells = new HashSet<>(environment.getAssetAdministrationShells());
Set<InternalElement> shellInternalElements = mapper.mapAsSet(administrationShells, InternalElement.class);

List factory mapper

factory.classMap(AssetAdministrationShell.class, InternalElement.class)
                .mapNulls(true)
                .mapNullsInReverse(true)
                .fieldMap("derivedFrom", "attribute[0]")
                .converter(DerivedFromToAttributeConverter.class.getName()).add()
                .fieldMap("identification", "attribute[1]")
                .converter(IdentificationToAttributeConverter.class.getName()).add()

Set factory mapper that does not work yet

factory.classMap(AssetAdministrationShell.class, InternalElement.class)
                .mapNulls(true)
                .mapNullsInReverse(true)
                .fieldMap("derivedFrom", "attribute{}")
                .converter(DerivedFromToAttributeConverter.class.getName()).add()
                .fieldMap("identification", "attribute{}")
                .converter(IdentificationToAttributeConverter.class.getName()).add()