...

1. An OTRS commend can be created by selecting OTRS Comment in the "More" menu.
    
   The "Add a comment to the OTRS Ticket" dialog is displayed.
   
2. In the "Add a comment to the OTRS Ticket" dialog, you can enter the subject and the comment itself. As long as there is no subject the comment can not be submitted.
3. Select the "External note" checkbox to mark the comment as external note (which customers can see) in OTRS. The comment also appears at the JIRA issue.

    

Via the JIRA standard commend

...