application.js

import DS from 'ember-data';
import {RSVP} from 'ember';

var Adapter = DS.RESTAdapter.extend({

  namespace: 'api/v1',

  findAll: function(store, type, sinceToken) {
    var url = this.buildURL(type.typeKey);
    var cached = localStorage.getItem(url);
    if (cached) {
      return new RSVP.Promise(function(resolve) {
        this.ajax(url, 'GET').then(function(res) {
          localStorage.setItem(url, JSON.stringify(res));
          store.pushMany(type, res);
        });
        return resolve(JSON.parse(cached));
      }.bind(this));
    } else {
      return this._super.apply(this, arguments).then(function(data, xhr) {
        localStorage.setItem(url, JSON.stringify(data));
        return data;
      });
    }
  }

});

export default Adapter;

Why is {RSVP} wrapped in curly braces?