/**
  * @param Field $field
  *
  * @return array
  */
 private function mapCollection(Field $field)
 {
     /** @var Collection $value */
     $value = $field->getValue();
     $getter = $field->getGetterName();
     if (!empty($getter)) {
         $values = array();
         foreach ($value as $relatedObj) {
             $values[] = $relatedObj->{$getter}();
         }
         return $values;
     }
     $collection = array();
     foreach ($value as $object) {
         $metaInformation = $this->metaInformationFactory->loadInformation($object);
         $field = array();
         $document = $this->createDocument($metaInformation);
         foreach ($document as $fieldName => $value) {
             $field[$fieldName] = $value;
         }
         $collection[] = $field;
     }
     return $collection;
 }