js/libs/ember-data.js
function(store, record, url) {
    var host = get(this, 'host'),
        id   = get(record, 'id'),
        type = record.constructor.typeKey;

    if (host && url.charAt(0) === '/' && url.charAt(1) !== '/') {
      url = host + url;
    }

    return this.ajax(this.urlPrefix(url, this.buildURL(type, id)), 'GET');
  }
function(store, record, url) {
    var host = get(this, 'host'),
        id   = get(record, 'id'),
        type = record.constructor.typeKey;

    if (host && url.charAt(0) === '/' && url.charAt(1) !== '/') {
      url = host + url;
    }

    return this.ajax(this.urlPrefix(url, this.buildURL(type, id)), 'GET');
  }
Called by the store in order to fetch a JSON array for
the unloaded records in a has-many relationship that were originally
specified as a URL (inside of `links`).

For example, if your original payload looks like this:

```js
{
"post": {
"id": 1,
"title": "Rails is omakase",
"links": { "comments": "/posts/1/comments" }
}
}
```

This method will be called with the parent record and `/posts/1/comments`.

The `findHasMany` method will make an Ajax (HTTP GET) request to the originally specified URL.
If the URL is host-relative (starting with a single slash), the
request will use the host specified on the adapter (if any).

@method findHasMany
@param {DS.Store} store
@param {DS.Model} record
@param {String} url
@returns {Promise} promise