public function add(AttachmentCreationInformation $information)
    {
        $attachment = new Attachment($this->getContext(),$this->getResourcePath());
        $qry = new InvokePostMethodQuery(
            $this->getResourcePath(),
            "add",
            array("FileName" =>rawurlencode($information->FileName)),
            $information->ContentStream);
        $this->getContext()->addQuery($qry,$attachment);
        $this->addChild($attachment);
        return $attachment;
    }