Wiki markup is not rendered in the Introduction gadget

Summary

Wiki markup added to the Introduction field in the General Configuration page is not rendered when viewed in the Introduction gadget

Steps to Reproduce

1. Navigate to Jira administration >> System >> General configuration
2. Edit Settings
3. Turn OFF the 'Enable HTML in custom field descriptions and list item values' option
   This changes the behavior of the Introduction field to show the following description in which suggests Wiki markup

   A short introduction message displayed on the dashboard.
   You can include Wiki markup.

4. In the Introduction field, add the following

   h2. This is heading 2
   
   h3. This is heading 3
   
   *This is supposed to be bold*
   
   _While this is italic_
   
   || Item || Location ||
   | *URL* | http://localhost:8080 |
   

1. Verify that the preview is rendering the wiki markup correctly
2. Save settings
3. View the Introduction gadget from the dashboard

Expected Results

Wiki markup is rendered as per the Preview

Actual Results

Wiki markup is not rendered in the Introduction gadget

Notes on fix (8.20.22, 9.8.0, 9.4.6 and onwards)

Since 8.20.22, 9.4.6, 9.8.0, Jira will render Wiki Markup on the introduction field.

HTML will be allowed depending upon the option set in the Jira administration -> System -> Edit Settings -> Enable HTML in custom field descriptions and list item values. To allow HTML in the Introduction field, this option needs to be turned ON this option (by default it's turned OFF). 

Having the said option above set to OFF will show HTML in plain text, and render only Wiki Markup. This change has been made to ensure that HTML is only allowed when explicitly allowed by the administrators.