/**
  * Fills the data with the proper characteristic type.
  *
  * @param \Doctrine\Common\Collections\Collection $data
  * @param \Ekyna\Component\Characteristics\Schema\Definition $definition
  * @throws \InvalidArgumentException
  */
 private function appendProperData(Collection $data, Definition $definition)
 {
     $identifier = $definition->getIdentifier();
     if ($data->offsetExists($identifier)) {
         return;
     }
     $characteristic = $this->manager->createCharacteristicFromDefinition($definition);
     $data->set($identifier, $characteristic);
 }