etReference-java.lang.Class-java.lang.Object-"><code>EntityManager.getReference</code></a>
 is accessed but the entity does not exist. Thrown when
 <a href="../../javax/persistence/EntityManager.html#refresh-java.lang.Object-"><code>EntityManager.refresh</code></a> is called and the
 object no longer exists in the database. 
 Thrown when <a href="../../javax/persistence/EntityManager.html#lock-java.lang.Object-javax.persistence.LockModeType-"><code>EntityManager.lock</code></a> is used with
 pessimistic loc