The changes to `getEmailCampaign` breaks (at least) the `recipients` and `statistics` fields.

[tasinttttttt]

The changes to getEmailCampaign breaks (at least) the recipients and statistics fields.

Steps to reproduce:

$config = Client\Configuration::getDefaultConfiguration()->setApiKey('api-key', 'API-KEY');
$apiInstance = new \SendinBlue\Client\Api\EmailCampaignsApi(
  new \GuzzleHttp\Client(),
  $config
);
$campaign = $apiInstance->getEmailCampaign($id);
// results recipients having a GetSmsCampaignRecipients type with an empty content

$campaign->getRecipients(); // results in empty

Last working comit is 74d4b0f

Originally posted by @tasinttttttt in #219 (comment)

[preetishishodia7]

Hi @tasinttttttt We have fixed this it now. Thanks for commenting.