/**
  * @param Fieldset $fieldset
  */
 protected function handleCollections(Fieldset $fieldset)
 {
     foreach ($fieldset->getFieldsets() as $childFieldset) {
         // Configure collection:
         if ($childFieldset instanceof Collection) {
             $this->configureInputFilter($childFieldset);
         }
         // Search deeper:
         $this->handleCollections($childFieldset);
     }
 }