to the
 client or when an unmapped throwable has been propagated to the hosting I/O
 container.
 <p>
 An unmapped throwable is propagated to the hosting I/O container in case no
 <a href="../../../../javax/ws/rs/ext/ExceptionMapper.html" title="interface in javax.ws.rs.ext"><code>exception mapper</code></a> has been found for
 a throwable indicating a request processing failure.
 In this case a non-<code>null</code> unmapped throwable instance is passed to the method.
 Note that the throwable instance repre