Generates the require_once statement for service includes.
string $id The service id:
Definition $definition:
string
private function addServiceInclude($id, $definition) {
  $template = "        require_once %s;\n";
  $code = '';
  if (null !== ($file = $definition
    ->getFile())) {
    $code .= sprintf($template, $this
      ->dumpValue($file));
  }
  foreach ($this
    ->getInlinedDefinitions($definition) as $definition) {
    if (null !== ($file = $definition
      ->getFile())) {
      $code .= sprintf($template, $this
        ->dumpValue($file));
    }
  }
  if ('' !== $code) {
    $code .= "\n";
  }
  return $code;
}