Hypertext Application Language grouping items in a collection

For the purposes of this question I can use an example document straight from the HAL spec, since my problem is very similar:

{
     "_links": {
       "self": { "href": "/orders" },
       "next": { "href": "/orders?page=2" },
       "find": { "href": "/orders{?id}", "templated": true }
     },
     "_embedded": {
       "orders": [{
           "_links": {
             "self": { "href": "/orders/123" },
             "basket": { "href": "/baskets/98712" },
             "customer": { "href": "/customers/7809" }
           },
           "total": 30.00,
           "currency": "USD",
           "status": "shipped",
         },{
           "_links": {
             "self": { "href": "/orders/124" },
             "basket": { "href": "/baskets/97213" },
             "customer": { "href": "/customers/12369" }
           },
           "total": 20.00,
           "currency": "USD",
           "status": "processing"
       }]
     },
     "currentlyProcessing": 14,
     "shippedToday": 20
   }

Under "embedded" there is "orders" which then has a list of orders. Suppose that I knew that I would often want to see a list of all orders where the currency is "USD". If I were to group the orders by currency, would that be permissible under HAL? I show an example of what I mean below. I don't want to use query parameters for filtering. The only other alternative that I can think of is looping over the whole list to pull out the orders with currency "USD". But that is very inefficient for large lists.

{
     "_links": {
       "self": { "href": "/orders" },
       "next": { "href": "/orders?page=2" },
       "find": { "href": "/orders{?id}", "templated": true }
     },
     "_embedded": {
       "orders": {"USD": [{
           "_links": {
             "self": { "href": "/orders/123" },
             "basket": { "href": "/baskets/98712" },
             "customer": { "href": "/customers/7809" }
           },
           "total": 30.00,
           "currency": "USD",
           "status": "shipped",
         },{
           "_links": {
             "self": { "href": "/orders/124" },
             "basket": { "href": "/baskets/97213" },
             "customer": { "href": "/customers/12369" }
           },
           "total": 20.00,
           "currency": "USD",
           "status": "processing"
       }], 
       "ZAR": []}
     },
     "currentlyProcessing": 14,
     "shippedToday": 20
   }