ntBehaviorHolder</code></a> to simplify subclass implementations. Subclasses that
 wish to support the <a href="../behavior/ClientBehaviorHolder.html" title="interface in jakarta.faces.component.behavior"><code>ClientBehaviorHolder</code></a> contract must declare that the
 subclass implements <a href="../behavior/ClientBehaviorHolder.html" title="interface in jakarta.faces.component.behavior"><code>ClientBehaviorHolder</code></a>, and must override this method to
 return a non-Empty <code>Collection</code>