The pages for types do not have a <h1> header. This is reported as an accessibility issue.

This file is a representative sample:
https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Object.html

Here's the source at the beginning of main:

<!-- ======== START OF CLASS DATA ======== -->
<main role="main">
<div class="header">
<div class="subTitle"><span class="moduleLabelInType">Module</span>&nbsp;<a href="../../module-summary.html">java.base</a></div>
<div class="subTitle"><span class="packageLabelInType">Package</span>&nbsp;<a href="package-summary.html">java.lang</a></div>
<h2 title="Class Object" class="title">Class Object</h2>
</div>

https://dequeuniversity.com/rules/axe/3.0/page-has-heading-one?application=webdriverjs

There are 1415 instances on this in the ltest Axe report.