title: Java - Openjpa: how to specify sequence generator starting from hibernate hbm
body: <p>I've to switch persistence of a project using <strong>HIBERNATE</strong> to <strong>OPENJPA</strong> and I started from  entities and hbm files which define type of columns, etc. 
  I've an Id on hibernate generated in this way:</p>
  
  <pre><code>&lt;id name="id" type="java.lang.Integer"&gt;
        &lt;column name="id"/&gt;
        &lt;generator class="sequence"&gt;
          &lt;param name="sequence"&gt;seq_illness&lt;/param&gt;
        &lt;/generator&gt;
      &lt;/id&gt;
  </code></pre>
  
  <p>how can I "translate" it ointo Jpa annotation to my entity class, in particular how can I represent sequence generator? 
  I'm new to this feature and I don't understand well usage of </p>
  
  <pre><code>@GeneratedValue(strategy = GenerationType.SEQUENCE)
  </code></pre>
  
  <p>how can I reproduce sequence parameter and define the correct sequence generator?</p>