title: Angular 2 optional route parameter
body: <p>Is it possible to have an optional route parameter in the Angular 2 route? I tried the Angular 1.x syntax in RouteConfig but received below error: </p>
  
  <blockquote>
    <p>"ORIGINAL EXCEPTION: Path "/user/:id?" contains "?" which is not allowed in a route config."</p>
  </blockquote>
  
  <pre><code>@RouteConfig([
  {
      path: '/user/:id?',
      component: User,
      as: 'User'
  }])
  </code></pre>