While creating request from portal form or email, add attachments on Jira Service Management will include the attachments as a comment, but not trigger the customer notification for that comment

Issue Summary

If an agent create a request from Jira Service Management portal form on behalf of a customer, and add a attachment to the attachment field. It will add the attachment as a comment, but not trigger the customer notification for that comment.

Steps to Reproduce

1. Log in as an agent
2. Go to customer portal
3. Find a request with attachment field
4. Add attachments from request form
   1. (If creating from an agent, select a customer in the "on behalf of" field)
5. Submit the request

Alternatively,

1. Send an incoming email to the Jira Service Management project, with attachments in the email.

Expected Results

1. The attachments is added as a comment by the request creator to the request
2. Customer get notification for the creation of the request
3. Customer get notification for the comment with the attachment

Actual Results

1. The attachment is added as a comment by the request creator to the request
2. Customer get notification for the creation of the request 
3. Customer DOES NOT get notification for the comment with the attachments

Workaround

Add another comment with the attachment, in order to trigger the notification with the attachment.