title: Polymorphism in GraphQL with a one-to-many relationship
body: <p>I have the following entities in my schema. </p>
  
  <ul>
  <li>User</li>
  <li>Link Post</li>
  <li>Normal Post</li>
  </ul>
  
  <p>How do I model the one to many relationship between the <code>User</code> and <code>Post</code> types where <code>Post</code> can be of the two types <code>LinkPost</code> or <code>NormalPost</code>.</p>