[xwiki-devs] HTMLCleaner to remove some iframes?

Hello fellow xwiki developers, trying to understand why an iframe element disappears after we re-edit source after we insert the iframe in source html, I seem to understand that the service called "HTMLCleaner" is the guilty one (the service is called as a POST to URL /xwiki/resources/js/xwiki/wysiwyg/xwe/HTMLConverter.gwtrpc Is there any way to configure the policy of the html-cleaner? I did not see this among the configs. thanks in advance. paul