What does ngInject do in the following piece of code? : <p>AngularJS controller code:</p>

<pre><code>function AuthConfig($stateProvider, $httpProvider) {
  'ngInject';

  // Define the routes
  $stateProvider

  .state('app.login', {
    url: '/login',
    templateUrl: 'auth/auth.html',
    title: 'Sign in'
  })

  .state('app.register', {
    url: '/register',
    templateUrl: 'auth/auth.html',
    title: 'Sign up'
  });

};

export default AuthConfig;
</code></pre>

<p>I am not able to figure out what is the use of ngInject. Could someone please help me?</p>
