session.js

import Ember from 'ember';
import SessionService from 'ember-simple-auth/services/session';

export default SessionService.reopen({
  jwt: {},

  // my problem is with this computed property. It is defined as a computed property, 
  // but when accessed, it is always undefined
  isAdmin: Ember.computed('jwt', function() {
    debugger; // this line is never hit
    !!this.get('jwt.is_admin');
  }),

  _jwtObserver: Ember.observer('data.authenticated', Ember.on('init', function() {
    const accessToken = this.get('data.authenticated.access_token');
    if (!Ember.isBlank(accessToken)) {
      if (Ember.isBlank(accessToken)) { return; }
      let parts = accessToken.split('.'),
        json = window.atob(parts[1]),
        hash = JSON.parse(json);

      this.set('jwt', hash);
    }
  }))
});