/**
  * {@inheritdoc}
  */
 public function build()
 {
     $link = parent::build();
     $source = $this->getSource();
     if ($source->containsKey('description')) {
         $link['description'] = $source['description'];
     }
     $destination = $this->getDestination();
     if ($destination->hasParent()) {
         $link['parent'] = $destination->getParent()->getIdentifier();
     }
     return $link;
 }
 /**
  * {@inheritdoc}
  */
 public function build()
 {
     $link = parent::build();
     $link['appears_on'][] = $this->getDestination()->getIdentifier();
     return $link;
 }