Exception</a></code> - in case the event source has already been opened earlier.</dd>
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<h4>isOpen</h4>
<pre class="methodSignature">boolean&nbsp;isOpen()</pre>
<div class="block">Check if this event source instance has already been <a href="#open()"><code>opened</code></a>.</div>
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<dt><span class="returnLabel">Returns:</span></dt>
<dd><code>true</code> if this event source is open, <code>false</code> otherwi