Common/Model/Notify.php
public function addAttachment(AttachmentInterface $attachment)
    {
        if (!$this->attachments->contains($attachment)) {
            $this->attachments->add($attachment);
        }

        return $this;
    }
public function addAttachment(AttachmentInterface $attachment)
    {
        if (!$this->attachments->contains($attachment)) {
            $this->attachments->add($attachment);
        }

        return $this;
    }
Adds the attachment.

@param AttachmentInterface $attachment

@return Notify