title: Jackson does not serialize subclass properly
body: <p>I am using Jackson to serialize Java objects for rest api. In Java I have an User class from which inherits Admin class.
  If I request data from ReactJS through method that returns <code>Collection&lt;User&gt;</code> I get only <code>id</code> for Admin objects.</p>
  
  <p>Here is my <strong>User</strong> class:</p>
  
  <pre><code>@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "id")
  @NamedQueries(
          @NamedQuery(name = "User.findByName",
              query = "SELECT u FROM User u WHERE u.firstName = :firstName AND u.lastName = :lastName"))
  @Entity
  @Table(name = "users")
  @Inheritance(strategy = InheritanceType.SINGLE_TABLE)
  @DiscriminatorColumn(name = "user_type")
  public class User extends AbstractEntity {
  
  @Basic(optional = false)
  @Column(nullable = false, name = "first_name")
  private String firstName;
  
  @Basic(optional = false)
  @Column(nullable = false, name = "last_name")
  private String lastName;
  
  @Basic(optional = false)
  @Column(nullable = false, unique = true)
  private String email;
  ...
  </code></pre>
  
  <p>Then I have <strong>Admin</strong> class:</p>
  
  <pre><code>@Entity
  public class Admin extends User {
  }
  </code></pre>
  
  <p>I expect to receive JSON objects in same form for Admin as for User, but Admin objects are serialized just with <code>id</code> and nothing else.</p>
  
  <p>Does it require any additional configuration for Jackson?</p>
  
  <p>I guess it has something incommon with this <a href="https://stackoverflow.com/questions/34193177/why-does-jackson-polymorphic-serialization-not-work-in-lists">question</a></p>