XML-Editor in JOE throws "Attribute '__comment__' is not allowed" error

The XML editor in JOE (mouse-over Job, contextMenu, 'Edit XML') returns following error messsage, after a change in XML has been made and 'Apply' clicked in Editor window:
Error in sos.scheduler.editor.app.TreeManu.applyXMLChange(508) ... Error on line49:cvc-complex-type.3.2.2: Attribute '_comment_' is not allowed to appear in element 'job'.)

Note that:

• The '_comment_' attribute appears to be added by JOE itself and is neither in the original JS object foles nor is it shown in the job Edit XML window. The attribute can, however, be seen when the 'Show Configuration as XML' icon at the top of the JOE window is clicked, after the change.

For example:
<job title="Execute PL/SQL procedure" order="yes" stop_on_error="no" name="execute_pf" _comment_="Removed Java ClassName: - sos.scheduler.db.JobSchedulerPLSQLJobJSAdapterClass">

This bug is triggered in the data set attached by the following lines in the 'execute_pf.job.xml' file:
<!-- Removed Java ClassName: - sos.scheduler.db.JobSchedulerPLSQLJobJSAdapterClass -->
Delete these lines and the XML edit function works as intended.

Bug confirmed by UR.

Attached:

• The contents of a 'live' folder with which this bug can be reproduced.
  (Use the XML editor to modify the 'aquire_lock' job as described above)