/**
  * {@inheritdoc}
  */
 protected function normalizeRequirements(FamilyInterface $family)
 {
     $requirements = parent::normalizeRequirements($family);
     $flat = [];
     foreach ($requirements as $key => $attributes) {
         $flat[$key] = implode(',', $attributes);
     }
     return $flat;
 }
 /**
  * {@inheritdoc}
  */
 protected function normalizeRequirements(FamilyInterface $family)
 {
     $requirements = parent::normalizeRequirements($family);
     $flat = array();
     foreach ($requirements as $channel => $attributes) {
         $flat[] = $channel . ':' . implode(',', $attributes);
     }
     return implode('|', $flat);
 }