title: JPA @OneTomany @ManyToOne mutliple instances
body: <p>For a tournament manager project, I have a tournament class which contains a list for Rounds.
  For treatment purpose, I have the reverse reference, the round knows its tournament.</p>
  <p>So I defined @OneToMany and @ManyToOne relations</p>
  <pre><code>class Tournament
  {
  @OneToMany (mappedBy=&quot;tournament&quot;)
  private List&lt;Round&gt; mRounds;
  }
  </code></pre>
  <pre><code>class Round
  {
  @ManyToOne
  private Tournament tournament;
  }
  </code></pre>
  <p>But the tournament is instanciated twice. The parent tournament is not the same which is contained by the Round instance (even if the Id is the same). How can I setup the JPA relationships to ensure that the same instance is used.</p>