private function getStructureRepresentation(Tracker $tracker)
 {
     $structure_element_representations = array();
     $form_elements = $this->formelement_factory->getUsedFormElementForTracker($tracker);
     if ($form_elements) {
         foreach ($form_elements as $form_element) {
             $structure_element_representation = new StructureElementRepresentation();
             $structure_element_representation->build($form_element);
             $structure_element_representations[] = $structure_element_representation;
         }
     }
     return $structure_element_representations;
 }