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                <section class="desc markdown">
          <p>The callback which is called when the stream is canceled.</p>
<p>May be set to <code>null</code>, in which case no callback will happen.</p>
        </section>
                <section class="summary source-code" id="source">
          <h2><span>Implementation</span></h2>
          <pre class="language-dart"><code class="language-dart">ControllerCancelCallback get onCancel;</code></pre>
        </section>
</section>
        
