code: public function getFileContent($file, $identifier)
      {
          $resource = sprintf('%s:%s', ProcessExecutor::escape($identifier), ProcessExecutor::escape($file));
          $this->process->execute(sprintf('git show %s', $resource), $content, $this->repoDir);
  
          if (!trim($content)) {
              return null;
          }
  
          return $content;
      }
docs: {@inheritdoc}