This macro is an old one but was done as a XAR attachments on extensions.xwiki.org.
Here’s what I’ve done:
- I’ve now moved this extension to xwiki-contrib under GitHub - xwiki-contrib/macro-sequence: Draw UML Sequence Diagrams (which will allow users to provide Pull Requests for it in the future :))
- There’s now a JIRA project for it at Loading... which allows users to report issues or suggest new ideas
- I’ve fixed the HTTPS issue and several others (see the release notes at http://extensions.xwiki.org/xwiki/bin/view/Extension/Sequence%20Diagram%20Macro#HReleaseNotes
Enjoy