title: Firebase Firestore, get the reference document inside another document
body: <p>I'm using <code>Firebase Cloud Firestore</code>, I want when I'm getting a document with reference field inside to receive the reference field as a document and not as a reference to the document...</p>
  
  <p>I have a collection of users and collection of classes (at school) and each class contains a list of references to users (the students in this class).
  When I using <code>document.get()</code> (to get the class by its reference) it returns an object that contains a list of <code>DocumentReference</code> (of the users) so I need to call <code>document.get()</code> around 20 more times just to get the users as objects and not as a reference to them.</p>
  
  <p>I want to be able to call <code>document.get()</code> once and it will bring me all the references as documents, like that:
  <a href="https://ibb.co/ee9bew" rel="noreferrer">database</a> and <a href="https://ibb.co/k0feXG" rel="noreferrer">code</a></p>
  
  <p>Is there an elegant way to do this?</p>