如果包含mime类型multipart / alternative或其他，则无法获取电子邮件正文

Question

I have implemented gmail APIs and every thing working perfect if mime type is text/html or text/plain but if mime type is multipart/alternative or any thing i am not able to get content.

Here is my code:

foreach ($message->getPayload()->getParts() as $part) {
   if($part->getMimeType() == "text/plain"){
      $email->body= $part->getBody()->getData();
    }
    elseif($part->getMimeType() == "text/html"){
        $email->body= $part->getBody()->getData();
    }
    elseif($part->getMimeType() == "multipart/alternative"){
         $email->body= $part->getBody()->getData();
    }
    else{
         $email->body= $part->getBody()->getData();
    }
}

Its not returning any thing.