code: function(sideloaded) {
          var store = get(this, 'store');
          var models = {};
          var serializer = this;
  
          sideloaded.forEach(function(link) {
            var type = link.type;
            if (link.relationships) {
              serializer.extractRelationships(link.relationships, link);
            }
            delete link.type;
            if (!models[type]) {
              models[type] = [];
            }
            models[type].push(link);
          });
  
          this.pushPayload(store, models);
        }
docs: Extract top-level "included" containing associated objects