AbstractAjaxTimerBehavior never triggers if attached to WebPage

Since WICKET-4886 was fixed, AbstractAjaxTimerBehavior never triggers anymore if it is added the the page itself.
See: org.apache.wicket.ajax.AbstractAjaxTimerBehavior.shouldTrigger()
getComponent().findParent(WebPage.class) != null
is always false in that case, which seems to be wrong. It should also be ok if the component itself is the WebPage.
So, the method should probably read something like

private boolean shouldTrigger()

{ return isStopped() == false && isEnabled(getComponent()) && (getComponent().findParent(WebPage.class) != null || getComponent() instanceof WebPage); }

Temporary workaround:
add the AbstractAjaxTimerBehavior to a subcomponent of the page instead.