/**
  * @param AnnotationInterface $child
  * @return Route
  */
 public function addChild(AnnotationInterface $child)
 {
     // trim leading slash from child route if parent is root route (/).
     if ($this->route == '/') {
         $child->setRoute(ltrim($child->getRoute(), '/'));
     }
     $this->children[] = $child;
     return $this;
 }