AttributeSet: PlainDescriptor<
    {
        collection: number;
        key: Binary;
        maybe_item?: number;
        namespace: Enum<
            {
                Account: SS58String;
                CollectionOwner: undefined;
                ItemOwner: undefined;
                Pallet: undefined;
            },
        >;
        value: Binary;
    },
>

New attribute metadata has been set for a collection or item.