Replaces service references by the real service instance.
mixed $value A value:
mixed The same value with all service references replaced by the real service instances
public function resolveServices($value) {
  if (is_array($value)) {
    foreach ($value as &$v) {
      $v = $this
        ->resolveServices($v);
    }
  }
  elseif ($value instanceof Reference) {
    $value = $this
      ->get((string) $value, $value
      ->getInvalidBehavior());
  }
  elseif ($value instanceof Definition) {
    $value = $this
      ->createService($value, null);
  }
  return $value;
}