n a Jakarta EE container, implementations are required to use the container-managed executor service by
 default. In Java SE, the default is implementation-specific. In either case, calling this method will override the
 default.</div>
<dl>
<dt><span class="paramLabel">Parameters:</span></dt>
<dd><code>executorService</code> - executor service to be used for async invocations.</dd>
<dt><span class="returnLabel">Returns:</span></dt>
<dd>an updated client builder instance.</dd>
<dt><span class="simpleTagLabel