JPA transaction exception getting real cause - nested exceptions
<p>I use openjpa and use store and commit.</p>

<p><em>Commit</em> sometimes launches exception, but I can't get more precisions.</p>

<p>Sometimes, I guess It's integrity problem (storing twice the same date).</p>

<p>The error message and the stack are:</p>

<pre><code>The transaction has been rolled back.  See the nested exceptions for details on the errors that occurred.
&lt;openjpa-2.4.1-r422266:1730418 fatal store error&gt; org.apache.openjpa.persistence.RollbackException: The transaction has been rolled back.  See the nested exceptions for details on the errors that occurred.
...
</code></pre>

<p><strong>But where to find more detailed causes, or how to get <em>nested exceptions</em> ?</strong></p>

<p>Thanks</p>