/**
  * @param Vertex $vertex
  * @return \Fhaculty\Graph\Edge\Directed
  */
 private function createEdgeToAdtRootVertexBy(Vertex $vertex)
 {
     foreach ($this->adtRootVertex->getEdges() as $edge) {
         /** @var \Fhaculty\Graph\Edge\Directed $edge */
         if ($edge->isConnection($this->adtRootVertex, $vertex)) {
             return $edge;
         }
     }
     return $this->adtRootVertex->createEdgeTo($vertex);
 }