REST Web Services - Return all fields from Content entity association
RESTws will retrieve your content using an Entity Metadata Wrapper. By default, this won't retrieve the referenced node. To get the nested content you'd need to write your own resource class in a custom module.

The new resource class is registered with hook_restws_resource_info().
 In your resource class, extend RestWSEntityResourceController or just implement RestWSQueryResourceControllerInterface (You can see the default implementation here.)

Your new resource class would look something like this:

class MyCustomResourceController extends RestWSEntityResourceController {

  /**
   * Override the wrapper method.
   */
  public function wrapper($id) {
    $wrapper = entity_metadata_wrapper($this-&gt;entityType, $id);
    /**Add something here to add the referenced node */
    return $wrapper;
  }

}