Supplemental UI partials to have Antora Default UI show author bylines

antora-playbook.yml

# snippet

ui:
  supplemental_files:
      # adds byline
    - path: partials/article.hbs
      contents: ./supplemental-ui/partials/article.hbs
    - path: partials/byline.hbs
      contents: ./supplemental-ui/partials/byline.hbs

article.hbs

<article class="doc">
{{#with page.title}}
<h1 class="page">{{{this}}}</h1>
{{/with}}
{{> byline}}
{{{page.contents}}}
{{> pagination}}
</article>

byline.hbs

{{#with (resolvePage page.relativeSrcPath model=false)}}
{{#unless (eq ./asciidoc.attributes.author undefined)}}
<div class="byline">
    {{#if (eq ./asciidoc.attributes.email undefined)}}
    <address class="author">By {{./asciidoc.attributes.author}}</a></address>
    {{else}}
    <address class="author">By <a rel="author" href="mailto:{{./asciidoc.attributes.email}}">{{./asciidoc.attributes.author}}</a></address>
    {{/if}}
</div>
{{/unless}}
{{/with}}

Example on how to produce a semantic HTML5 byline section with Antora's Default UI based on an author line in the AsciiDoc document:

= Page Title
Firstname Lastname <mail@domain.example>

Based on the suggested workaround in https://gitlab.com/antora/antora/-/issues/355

The above files would need to be put in partials/ and added as supplement to the default ui. See antora-playbook.yml-Snippet.