title: Inheritance using Abstract class in GraphQL schema
body: <p>I have following domain objects &amp; I am using spring boot support for GraphQL.</p>
  
  <pre><code>public abstract class User {
      private long id;
      private String email;
  }
  public class Person extends User {
      private String firstName;
      private String lastName;
      //getters &amp; setters
  }
  public class Company extends User {
      private String name;
      private String hqCity;
      //getters &amp; setters
  }
  </code></pre>
  
  <p>Now I want to fetch all users be it Person or Company. 
  How would I do that using graphql schema ? I tried for interface in graphQL but that does not work. Does graphQL supports this in some way ?</p>