Support for additional structure types for PDF tagging

When checking a document with `` tags, I noticed that they are just represented as span.
There seems to be a matching [structure type](https://pdfbox.apache.org/docs/2.0.2/javadocs/org/apache/pdfbox/pdmodel/documentinterchange/taggedpdf/StandardStructureTypes.html#CODE) – I'm not aware whether it might have been a later addition – but I don't see it used in the [PdfBoxAccessibilityHelper](https://github.com/danfickle/openhtmltopdf/blob/780ba564839f1ad5abfa5df12e4aebb9dd6782d2/openhtmltopdf-pdfbox/src/main/java/com/openhtmltopdf/pdfboxout/PdfBoxAccessibilityHelper.java).
Is this the correct place to look?
Browsing a bit through the code I don't see how to customize or subclass this. Is there a way to do this?