public function addEncryptedXmlAcceptanceCertificateSellerTitles(\AgentSIB\Diadoc\Api\Proto\Events\EncryptedXmlDocumentAttachment $value)
    {
        if ($this->EncryptedXmlAcceptanceCertificateSellerTitles === null) {
            $this->EncryptedXmlAcceptanceCertificateSellerTitles = new \Protobuf\MessageCollection();
        }

        $this->EncryptedXmlAcceptanceCertificateSellerTitles->add($value);
    }