ption.class</code>. If there is no root cause,
 <code>null</code> is returned.
 </p></div>
<dl class="notes">
<dt>Parameters:</dt>
<dd><code>t</code> - passed-in wrapped <code>Throwable</code>.</dd>
<dt>Returns:</dt>
<dd>unwrapped object.</dd>
<dt>Throws:</dt>
<dd><code><a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/NullPointerException.html" title="class or interface in java.lang" class="external-link">NullPointerException</a></code> - if argument <code>t</code> is <code>nu