/**
  * Get the real ID of the given object by it's metadata
  *
  * @param ClassMetadata $classMetadata
  * @param               $object
  *
  * @return mixed
  */
 protected function getId(ClassMetadata $classMetadata, $object)
 {
     $propertyAccessor = PropertyAccess::createPropertyAccessor();
     return $propertyAccessor->getValue($object, $classMetadata->getIdField());
 }