>
         that wraps all the exceptions raised by observers as suppressed exception.
         If no exception is thrown by observers then the resulting CompletionStage is completed normally with the event payload.</dd>
<dt><span class="throwsLabel">Throws:</span></dt>
<dd><code><a href="https://docs.oracle.com/javase/8/docs/api/java/lang/IllegalArgumentException.html?is-external=true" title="class or interface in java.lang">IllegalArgumentException</a></code> - if the runtime type of the event object conta