How to tag a hyperlink that is only part of a mixed inline/styled text run as a `Link` structure element (PDF/UA)?

[gvgramazio]

What I'm trying to do

Export a tagged PDF (PDF/UA) where a hyperlink covers only part of a sentence, e.g.:

Lorem ipsum dolor sit amet, consectetur adipiscing elit.

where only "adipiscing elit" should be a clickable link, and that link should be a properly nested Link structure element (not just a clickable /Link annotation), otherwise PDF/UA checkers (e.g. PAC) report: "Link annotation is not nested inside a Link structure element."

What works: linking the whole element

When the entire text of an element is the link target, this tags correctly:

<element kind="textField" uuid="f44d8ccb-580c-495c-9ac5-bc3b6bade20a"
         x="0" y="0" width="200" height="15"
         linkType="Reference" linkTarget="Self">
    <expression><![CDATA["lorem-ipsum.example/dolor"]]></expression>
    <hyperlinkReferenceExpression><![CDATA["https://lorem-ipsum.example/dolor"]]></hyperlinkReferenceExpression>
</element>

Inspecting the exported PDF's structure tree confirms the /Link annotation carries a /StructParent, and the corresponding Link tag in the structure tree references it back via OBJR. This matches how JRPrintText#getLinkType() is checked at the whole-element level by the tag-helper logic (JRPdfExporterTagHelper in the 7.0.7 CE implementation, or any PdfTagger SPI implementation since 7.0.8).

What doesn't tag correctly: inline <a> inside styled/mixed text

JasperReports' styled markup also lets you embed a hyperlink as an inline anchor inside a text element's rich content, e.g.:

<element kind="textField" uuid="9416616e-df13-452c-930e-5c53cc3944f4"
         x="0" y="0" width="400" height="15" markup="styled">
    <expression><![CDATA[
        "Lorem ipsum dolor sit amet, consectetur "
        + "<a href=\"https://lorem-ipsum.example/adipiscing\">adipiscing elit</a>."
    ]]></expression>
</element>

This does paint a real, clickable /Link annotation for "adipiscing elit" at export time, but it is never wrapped in a matching Link structure tag. I traced this to the net.sf.jasperreports.pdf.common.PdfTagger SPI itself: startText(JRPrintText) / startText(JRPrintText, String) only ever receive the whole print element and check its getLinkType(); there's no callback for a hyperlink run embedded inside styled text. So this can't be fixed from a custom PdfTagger plugin alone since the gap is in how JRPdfExporter paints inline anchor runs, upstream of the tagger hook.

The only workaround I've found: an invisible overlay hotspot

Render the visible text as a plain styled run that only looks like a link (underline + link color, no real hyperlink), then overlay a second, invisible, transparent element, hand-positioned/sized to match the rendered substring, that carries the real linkType:

<element kind="frame" uuid="a460861e-4047-4453-a4f2-054537353f2d" x="0" y="0" width="400" height="15">
    <!-- Visible text: styled to look like a link, carries no real hyperlink -->
    <element kind="textField" uuid="924ed60a-c6e4-4a80-8e3f-3119389a83dd"
             x="0" y="0" width="400" height="15" markup="styled">
        <expression><![CDATA[
            "Lorem ipsum dolor sit amet, consectetur "
            + "<style isUnderline='true' forecolor='#0000EE'>adipiscing elit</style>."
        ]]></expression>
    </element>
    <!-- Invisible overlay carrying the real link, manually positioned under "adipiscing elit" -->
    <element kind="textField" uuid="851a7d63-a1e3-4dd4-92e0-4d083c603fe1"
             x="238" y="0" width="70" height="15"
             mode="Transparent" forecolor="rgba(255,255,255,0.0)"
             linkType="Reference" linkTarget="Self">
        <expression><![CDATA["adipiscing elit"]]></expression>
        <hyperlinkReferenceExpression><![CDATA["https://lorem-ipsum.example/adipiscing"]]></hyperlinkReferenceExpression>
    </element>
</element>

This does tag correctly (the invisible element is, itself, a whole-element hyperlink), but it has real downsides:

• Brittle positioning. The overlay's x/width must be hand-measured in pixels against the rendered width of the visible substring. Any change in translated text length, font substitution, or font size breaks the alignment silently.
• Duplicated text. The same words exist twice in the content stream: once as a plain, non-interactive visible run, once as an invisible interactive run. Depending on how assistive tech handles zero-alpha/transparent text, this risks duplicate or confusing announcements, and shows up oddly in text extraction/copy-paste.
• Doesn't scale. Every "partial sentence is a link" occurrence needs its own manually tuned overlay; there's no way to parametrize this for dynamic, data-driven, or localized content.

The question

Is there a supported, first-class way to tag a hyperlink that covers only part of a mixed/styled text run as a proper Link structure element I'm missing? If not, would a feature request be in scope here: either extending the PdfTagger SPI with a per-run hyperlink hook, or having the built-in inline-<a>-to-annotation code path set /StructParent/OBJR the same way whole-element hyperlinks already do?

Environment: JasperReports 7.0.8, PDF export via jasperreports-pdf, tagged export enabled (net.sf.jasperreports.export.pdf.tagged=true).