Little Heap of Horrors skill challenge

Apex Script.cs

 //replace with the id of uploaded image
 ProductCreator.createProduct('[REPLACE]');

ProductCreator.cs

public class ProductCreator {

    //cannot modify signiture
    @future public static void createProduct(Id attchId){
        Attachment attch = [SELECT Name, Body FROM Attachment WHERE ID = :attchId];
        String image = EncodingUtil.base64Encode(attch.Body);
        HorrorProduct product = new HorrorProduct(attch.name, image);
        String body = JSON.serialize(product);
        HttpRequest req = createRequest('https://example.com/newProduct', 'POST', body);
        sendRequest(req);
    }

    private static HttpRequest createRequest(String endpoint, String method, String body){
        HttpRequest req = new HttpRequest();
        req.setEndpoint(endpoint);
        req.setBody(body);
        req.setMethod(method);
        return req;
    }

    public class HorrorProduct{
        public String name {get; set;}
        public String image {get; set;} //base64 encoded string

        public HorrorProduct(String name, String image){
            this.name = name;
            this.image = image;
        }
    }

    //DO NOT MODIFY ANYTHING BELOW THIS LINE.  Everything above is fair game!
    private static void sendRequest(HttpRequest req){
        System.assert(Limits.getHeapSize() < Limits.getLimitHeapSize(), 'Heap overallocated by ' + ((Limits.getHeapSize() - Limits.getLimitHeapSize())/1000) + ' kb');

        System.debug('Congratulations! You have ' + (Limits.getLimitHeapSize() - Limits.getHeapSize()) + ' bytes of heap memory remaining');
    }
}