code: protected function getIdentifierValue(ResourceInterface $originalData)
      {
          $class = ClassUtils::getClass($originalData);
          $entityManager = $this->doctrine->getManagerForClass($class);
          if (!$entityManager instanceof EntityManagerInterface) {
              throw new \InvalidArgumentException("No manager found for class {$class}");
          }
          $metadata = $entityManager->getClassMetadata($class);
          $identifier = $metadata->getIdentifierValues($originalData);
          if (1 !== \count($identifier)) {
              throw new \LogicException('ResourceInterface must have a single identifier (primary key)');
          }
  
          return array_pop($identifier);
      }
docs: @param ResourceInterface $originalData
  
  @throws \InvalidArgumentException
  @throws \LogicException
  
  @return array